Method and apparatus for transmitting and receiving reference signal in wireless communication system

ABSTRACT

The present invention relates to a wireless communication system and, more specifically, to a method and an apparatus for transmitting and receiving a reference signal (RS). The method for enabling user equipment (UE) of the wireless communication system to transmit an uplink signal according to one embodiment of the present invention comprises the steps of: receiving information on a plurality of parameter sets used for generating a sequence of RS; and generating and transmitting the sequence of the RS using one parameter set determined among the plurality of parameter sets. The parameters constituting the plurality of parameter sets can comprise the parameters commonly applied to the plurality of parameter sets and the parameters individually applied to the plurality of parameter sets.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is the National Phase of PCT/KR2013/002451 filed onMar. 25, 2013, which claims priority under 35 U.S.C. 119(e) to U.S.Provisional Application No. 61/615,276 filed on Mar. 24, 2012, to U.S.Provisional Application No. 61/615,880 filed on Mar. 26, 2012, to U.S.Provisional Application No. 61/617,676 filed on Mar. 30, 2012, to U.S.Provisional Application No. 61/677,469 filed on Jul. 30, 2012, to U.S.Provisional Application No. 61/679,062 filed on Aug. 2, 2012 and to U.S.Provisional Application No. 61/682,303 filed on Aug. 12, 2012, all ofwhich are incorporated by reference herein in its entirety.

TECHNICAL FIELD

The present invention relates to a wireless communication system and,more particularly, to a method and apparatus for transmitting andreceiving a reference signal.

BACKGROUND ART

To satisfy increasing data throughput in a wireless communicationsystem, Multiple Input Multiple Output (MIMO) technology, CoordinatedMulti-Point (CoMP) technology, etc. for increasing the amount of datatransmitted within a limited frequency band have been developed.

An enhanced wireless communication system which supports CoMP forallowing a plurality of evolved Node Bs (eNBs) to communicate with aUser Equipment (UE) using the same time-frequency resource can provideincreased data throughput compared to a legacy wireless communicationsystem in which a single eNB communicates with a UE. The eNBsparticipating in CoMP may be referred to as cells, antenna ports,antenna port groups, Remote Radio Heads (RRHs), transmission points,reception points, access points, etc.

DISCLOSURE Technical Problem

With the introduction of new wireless communication technology, thenumber of UEs to be served by an eNB in a predetermined resource regionis increased and the amount of data and control information to betransmitted to/received from the UEs is also increased. Since the amountof radio resource usable for communication with the UEs is finite, a newmethod for allowing the eNB to efficiently receive/transmituplink/downlink data and/or uplink/downlink control information from/tothe UEs using the finite radio resource is required.

An object of the present invention devised to solve the problem lies ina new method for transmitting and receiving an enhanced uplink/downlinkreference signal.

It is to be understood that both the foregoing general description andthe following detailed description of the present invention areexemplary and explanatory and are intended to provide furtherexplanation of the invention as claimed.

Technical Solution

The object of the present invention can be achieved by providing amethod for transmitting an uplink signal by a User Equipment (UE) in awireless communication system, the method including receivinginformation about a plurality of parameter sets used to generate asequence of a Reference Signal (RS), and generating and transmitting thesequence of the RS using one parameter set determined among theparameter sets, wherein each of the parameter sets includes a parametercommonly applied to the parameter sets and a parameter individuallyapplied to the parameter sets.

In another aspect of the present invention, provided herein is a UserEquipment (UE) for transmitting an uplink signal, the UE including areceiver, a transmitter, and a processor, wherein the processor isconfigured to receive information about a plurality of parameter setsused to generate a sequence of a Reference Signal (RS), using thereceiver, to generate the sequence of the RS using one parameter setdetermined among the parameter sets, and to transmit the RS using thetransmitter, and wherein each of the parameter sets includes a parametercommonly applied to the parameter sets and a parameter individuallyapplied to the parameter sets.

The followings may be commonly applied to the method and the UE.

The parameter sets may correspond to a plurality of reception points(RPs) to which the RS is directed.

When the RS is a Physical Uplink Control Channel (PUCCH) DemodulationReference Signal (DMRS), the parameter sets may correspond to aplurality of PUCCH format groups.

When the RS is a Sounding Reference Signal (SRS), the parameter sets maycorrespond to a plurality of SRS power control processes.

The commonly applied parameter may be a Virtual Cell Identifier (VCI).

The individually applied parameter may be a sequence shift offset(Δ_(ss)).

The parameter set may include a parameter commonly applied and aparameter individually applied within the parameter set.

When the RS is a Physical Uplink Shared Channel (PUSCH) DMRS, theparameter set may include a VCI configured to one of values from 0 to509. In this case, the parameter set may not include Δ_(ss).

A plurality of first RS parameter sets for a first type RS may becommonly configured with a plurality of second RS parameter sets for asecond type RS.

When the first RS parameter sets are signaled, the second RS parametersets may be not signaled.

The information about the parameter sets may be provided through higherlayer signaling.

The parameter set used to generate and transmit the RS among theparameter sets may be indicated using Downlink Control Information(DCI).

It is to be understood that both the foregoing general description andthe following detailed description of the present invention areexemplary and explanatory and are intended to provide furtherexplanation of the invention as claimed.

Advantageous Effects

According to the present invention, a new method for transmitting andreceiving an enhanced uplink/downlink reference signal may be provided.

It will be appreciated by persons skilled in the art that that theeffects that could be achieved with the present invention are notlimited to what has been particularly described hereinabove and otheradvantages of the present invention will be more clearly understood fromthe following detailed description taken in conjunction with theaccompanying drawings.

DESCRIPTION OF DRAWINGS

The accompanying drawings, which are included to provide a furtherunderstanding of the invention, illustrate embodiments of the inventionand together with the description serve to explain the principle of theinvention. In the drawings:

FIG. 1 is a view for describing the structure of a radio frame;

FIG. 2 is a view illustrating a resource grid;

FIG. 3 is a view illustrating the structure of a downlink subframe;

FIG. 4 is a view for describing a downlink reference signal;

FIG. 5 is a view illustrating the structure of an uplink subframe;

FIGS. 6 to 10 illustrate Uplink Control Information (UCI) transmissionusing Physical Uplink Control Channel (PUCCH) format 1 series, PUCCHformat 2 series and PUCCH format 3 series;

FIG. 11 illustrates multiplexing of UCI and uplink data in a PhysicalUplink Shared Channel (PUSCH) region;

FIG. 12 is a view for describing an exemplary Uplink (UL) CoordinatedMulti-Point (CoMP) operation;

FIG. 13 is a flowchart of a method for transmitting and receiving aReference Signal (RS), according to an embodiment of the presentinvention; and

FIG. 14 is a block diagram of a UE and an eNB according to an embodimentof the present invention.

BEST MODE

The embodiments of the present invention described hereinbelow arecombinations of elements and features of the present invention. Theelements or features may be considered selective unless otherwisementioned. Each element or feature may be practiced without beingcombined with other elements or features. Further, an embodiment of thepresent invention may be constructed by combining parts of the elementsand/or features. Operation orders described in embodiments of thepresent invention may be rearranged. Some constructions or features ofany one embodiment may be included in another embodiment and may bereplaced with corresponding constructions or features of anotherembodiment.

In the embodiments of the present invention, a description is given,centering on a data transmission and reception relationship between aBase Station (BS) and a User Equipment (UE). The BS is a terminal nodeof a network, which communicates directly with a UE. In some cases, aspecific operation described as performed by the BS may be performed byan upper node of the BS.

Namely, it is apparent that, in a network comprised of a plurality ofnetwork nodes including a BS, various operations performed forcommunication with a UE may be performed by the BS or network nodesother than the BS. The ‘BS’ may be replaced with the term ‘fixedstation’, ‘Node B’, ‘evolved Node B (eNode B or eNB)’ or ‘Access Point(AP)’. The term ‘relay’ may be replaced with the term ‘Relay Node (RN)’or ‘Relay Station (RS)’. The term ‘terminal’ may be replaced with theterm ‘UE’, ‘Mobile Station (MS)’, ‘Mobile Subscriber Station (MSS)’ or‘Subscriber Station (SS)’.

Specific terms used in the embodiments of the present invention areprovided to aid in the understanding of the present invention. Thesespecific terms may be replaced with other terms within the scope andspirit of the present invention.

In some instances, to prevent the concept of the present invention frombeing ambiguous, structures and apparatuses of the known art will beomitted, or will be shown in block diagram form based on main functionsof each structure and apparatus. In addition, wherever possible, likereference numerals denote the same parts throughout the drawings and thespecification.

The embodiments of the present invention can be supported by standarddocuments disclosed for at least one of wireless access systemsincluding Institute of Electrical and Electronics Engineers (IEEE) 802,3^(rd) Generation Partnership Project (3GPP), 3GPP Long Term Evolution(3GPP LTE), LTE-Advanced (LTE-A), and 3GPP2. Steps or parts that are notdescribed to clarify the technical features of the present invention canbe supported by these specifications. Further, all terms as set forthherein can be explained by the standard specifications.

Techniques described herein can be used in various wireless accesssystems such as Code Division Multiple Access (CDMA), Frequency DivisionMultiple Access (FDMA), Time Division Multiple Access (TDMA), OrthogonalFrequency Division Multiple Access (OFDMA), Single Carrier FrequencyDivision Multiple Access (SC-FDMA), etc. CDMA may be implemented as aradio technology such as Universal Terrestrial Radio Access (UTRA) orCDMA2000. TDMA may be implemented as a radio technology such as GlobalSystem for Mobile communications (GSM)/General Packet Radio Service(GPRS)/Enhanced Data Rates for GSM Evolution (EDGE). OFDMA may beimplemented as a radio technology such as IEEE 802.11 (Wi-Fi), IEEE802.16 (WiMAX), IEEE 802.20, Evolved-UTRA (E-UTRA) etc. UTRA is a partof Universal Mobile Telecommunications System (UMTS). 3GPP LTE is a partof Evolved UMTS (E-UMTS) using E-UTRA. 3GPP LTE employs OFDMA forDownlink (DL) and SC-FDMA for Uplink (UL). LTE-A is an evolution of 3GPPLTE. WiMAX can be described by the IEEE 802.16e standard (WirelessMetropolitan Area Network (WirelessMAN)-OFDMA Reference System) and theIEEE 802.16m standard (WirelessMAN-OFDMA Advanced System). For clarity,the present disclosure focuses on the 3GPP LTE and LTE-A systems.However, the technical features of the present invention are not limitedthereto.

A description is now given of the structure of a radio frame in the 3GPPLTE system with reference to FIG. 1.

In a cellular Orthogonal Frequency Division Multiplexing (OFDM) wirelesspacket communication system, UL/DL data packets are transmitted on asubframe basis and a subframe is defined as a certain time periodincluding a plurality of OFDM symbols. The 3GPP LTE standard supports atype-1 radio frame structure applicable to Frequency Division Duplex(FDD) and a type-2 radio frame structure applicable to Time DivisionDuplex (TDD).

FIG. 1(a) is a view illustrating the type-1 radio frame structure. Aradio frame includes 10 subframes and a subframe includes two slots inthe time domain. A time taken to transmit a subframe is defined as aTransmission Time Interval (TTI). For example, the length of a subframemay be 1 ms and the length of a slot may be 0.5 ms. A slot includes aplurality of OFDM symbols in the time domain and a plurality of ResourceBlocks (RBs) in the frequency domain. Since the 3GPP LTE system usesOFDMA for downlink, an OFDM symbol represents a symbol period. An OFDMsymbol may also be referred to as an SC-FDMA symbol or a symbol period.An RB is a resource allocation unit and a slot may include a pluralityof contiguous subcarriers.

The number of OFDM symbols included in a slot may vary depending on theconfiguration of a Cyclic Prefix (CP). There are two types of CPs: anextended CP and a normal CP. In the case of the normal CP, a slot mayinclude 7 OFDM symbols. In the case of the extended CP, the length of anOFDM symbol is increased and thus the number of OFDM symbols included ina slot is smaller than in the case of the normal CP. When the extendedCP is used, for example, 6 OFDM symbols may be included in a slot. In aninstable channel state, for example, when a UE moves fast, the extendedCP may be used to further decrease Inter-Symbol Interference (ISI).

FIG. 1(b) is a view illustrating the type-2 radio frame structure. Thetype-2 radio frame includes 2 half frames each including 5 subframes, aDownlink Pilot Time Slot (DwPTS), a Guard Period (GP) and an UplinkPilot Time Slot (UpPTS). A subframe includes 2 slots. The DwPTS is usedfor initial cell search, synchronization or channel estimation at a UE.The UpPTS is used for channel estimation and acquisition of ULtransmission synchronization to a UE at an eNB. The GP is a periodbetween UL and DL, which eliminates UL interference caused by multipathdelay of a DL signal. 1 subframe includes 2 slots irrespective of theradio frame type.

The above-described radio frame structures are purely exemplary and thenumber of subframes included in a radio frame, the number of slotsincluded in a subframe, or the number of symbols included in a slot mayvary.

FIG. 2 is a view illustrating a resource grid for a DL slot. A DL slotmay include 7 OFDM symbols in the time domain and an RB may include 12subcarriers in the frequency domain. However, the present invention isnot limited thereto. For example, a slot may include 7 OFDM symbols inthe case of a normal CP but may include 6 OFDM symbols in the case of anextended CP. Each element of the resource grid is referred to as aResource Element (RE). An RB includes 12×7 REs. The number of RBsincluded in a DL slot, N^(DL) depends on a DL transmission bandwidth.The structure of a UL slot may be the same as that of the DL slot.

Downlink Subframe Structure

FIG. 3 is a view illustrating the structure of a DL subframe. Up to 3initial OFDM symbols of the first slot in a DL subframe correspond to acontrol region to which control channels are allocated and the otherOFDM symbols of the DL subframe correspond to a data region to which aPhysical Downlink Shared Chancel (PDSCH) is allocated. DL controlchannels used in the 3GPP LTE system include, for example, a PhysicalControl Format Indicator Channel (PCFICH), a Physical Downlink ControlChannel (PDCCH) and a Physical Hybrid automatic repeat request (HARQ)Indicator Channel (PHICH). The PCFICH is transmitted using the firstOFDM symbol of a subframe and carries information about the number ofOFDM symbols used for control channel transmission in the subframe. ThePHICH carries an HARQ ACKnowledgment/Negative ACKnowledgment (ACK/NACK)signal as a response to UL transmission. Control information transmittedon the PDCCH is referred to as Downlink Control Information (DCI). TheDCI includes UL or DL scheduling information, or UL Tx power controlcommands for an arbitrary UE group. The PDCCH may carry resourceallocation and transmission format information of a Downlink SharedChannel (DL-SCH), resource allocation information of an Uplink SharedChannel (UL-SCH), paging information of a Paging Channel (PCH), systeminformation on the DL-SCH, resource allocation information of ahigher-layer control message such as a random access responsetransmitted on the PDSCH, a set of Tx power control commands forindividual UEs within an arbitrary UE group, Tx power controlinformation, Voice over Internet Protocol (VoIP) enable information,etc. A plurality of PDCCHs may be transmitted in the control region. AUE may monitor a plurality of PDCCHs. A PDCCH is transmitted in anaggregation of one or more consecutive Control Channel Elements (CCEs).A CCE is a logical allocation unit used to provide a PDCCH at a codingrate based on the state of a radio channel. A CCE corresponds to aplurality of RE Groups (REGs). The format and number of available bitsof a PDCCH are determined based on the correlation between the number ofCCEs and a coding rate provided by the CCEs. An eNB determines a PDCCHformat based on DCI transmitted to a UE and adds a Cyclic RedundancyCheck (CRC) to the control information. The CRC is masked with anIdentifier (ID) such as a Radio Network Temporary Identifier (RNTI)based on the owner or purpose of the PDCCH. If the PDCCH is for aspecific UE, the CRC may be masked with a Cell-RNTI (C-RNTI) of the UE.Otherwise, if the PDCCH is for a paging message, the CRC may be maskedwith a Paging Indicator Identifier (P-RNTI). If the PDCCH is for systeminformation and, more particularly, a System Information Block (SIB),the CRC may be masked with a system information ID and a SystemInformation RNTI (SI-RNTI). To indicate a random access response to arandom access preamble transmitted by a UE, the CRC may be masked with aRandom Access-RNTI (RA-RNTI).

Downlink Reference Signal

Since packets are transmitted through a radio channel in a wirelesscommunication system, a signal may be distorted during transmission. Areceiver should correct the distorted signal using channel informationin order to correctly receive the distorted signal. To detect channelinformation, a signal known to both the receiver and a transmitter istransmitted and the channel information is detected using a degree ofdistortion of the signal when the signal is received on a channel. Thissignal is referred to as a pilot signal or a Reference Signal (RS).

When multiple antennas are used to transmit and receive data, a correctsignal can be received only when a channel state between each Tx antennaand each Rx antenna is detected. Accordingly, an RS is required for eachTx antenna.

There are two types of downlink reference signals: a Common ReferenceSignal (CRS) shared by all UEs in a cell and a Dedicated ReferenceSignal (DRS) dedicated to a specific UE. Information for channelestimation and demodulation can be provided by these RSs. The CRS isused to estimate a channel of a physical antenna and can be commonlyreceived by all UEs in a cell. The CRS is distributed over the entireband. The CRS can be used for Channel State Information (CSI)acquisition and data demodulation.

A receiver (UE) can estimate a channel state based on the CRS and feedback an indicator associated with channel quality, e.g., Channel QualityIndicator (CQI), Precoding Matrix Index (PMI) and/or Rank Indicator(RI), to a transmitter (eNB). The CRS may also be referred to as acell-specific RS.

The DRS can be transmitted through a corresponding RE when data on aPDSCH needs to be demodulated. Presence or absence of the DRS may besignaled to the UE from a higher layer, or a fact that the DRS is validonly when a corresponding PDSCH is mapped may be signaled to the UE. TheDRS may also be referred to as a UE-specific RS or a DemodulationReference Signal (DMRS). The DRS (or a UE-specific RS) is used for datademodulation. For transmission through multiple antennas, a precodingweight used for a specific UE is equally applied to RSs such that, whenthe UE receives the RSs, it may estimate equivalent channels in whichthe precoding weight applied to the respective Tx antennas are combinedwith transmission channels.

FIG. 4 is a view illustrating a pattern of mapping a CRS and a DRSdefined in 3GPP LTE (e.g., Release-8) to a downlink RB pair. A downlinkRB pair is a reference signal mapping unit and may be represented as 1subframe in the time domain×12 subcarriers in the frequency domain. Thatis, an RB pair has a length of 14 OFDM symbols in the case of a normalCP and has a length of 12 OFDM symbols in the case of an extended CP inthe time domain. FIG. 4 illustrates the RB pair in the case of thenormal CP.

FIG. 4 illustrates RS positions in RB pairs in a system in which an eNBsupports 4 Tx antennas. In FIG. 4, REs marked ‘R0’, ‘R1’, ‘R2’ and ‘R3’respectively represent CRS positions with respect to antenna portindices 0, 1, 2 and 3. An RE marked ‘D’ represents a DRS position.

LTE-A evolving from 3GPP LTE, considers high-order Multiple InputMultiple Output (MIMO), multi-cell transmission, enhanced multi-user(MU)-MIMO, etc. and also considers DRS based data demodulation tosupport efficient RS operation and enhanced transmission scheme. Thatis, separately from a DRS (antenna port index 5) for rank-1 beamforming,which is defined in 3GPP LTE (e.g., Release-8), a DRS (or UE-specific RSor DMRS) for two or more layers can be defined to support datatransmission through an added antenna. For example, UE-specific RS portssupporting up to 8 Tx antenna ports can be defined with antenna portnumbers 7 to 12 and the UE-specific RS can be transmitted at an REposition which does not overlap with other RSs.

In LTE-A, an RS associated with feedback of CSI such as CQI/PMI/RI for anew antenna port may be separately defined as a CSI-RS. For example,CSI-RS ports supporting up to 8 Tx antenna ports can be defined withantenna port numbers 15 to 22 and the CIS-RS can be transmitted at an REposition which does not overlap with other RSs.

When data is transmitted on a certain downlink subframe (e.g., PDSCHtransmission), a DM RS is transmitted dedicatedly to a UE scheduled fordata transmission. A DM RS dedicated to a specific UE (or a UE-specificRS) may be designed to be transmitted only in a resource regionscheduled for the UE, i.e., only in a time-frequency domain in whichdata for the UE is transmitted.

The UE-specific RS may be transmitted through an antenna port p=7, p=8,or p=7, 8, . . . , v+6, where v denotes the number of layers used forPDSCH transmission.

A UE-specific RS sequence r(m) may be defined as shown in Equation 1.

$\begin{matrix}{{r(m)} = {{\frac{1}{\sqrt{2}}\left( {1 - {2 \cdot {c\left( {2m} \right)}}} \right)} + {j\;\frac{1}{\sqrt{2}}\left( {1 - {2 \cdot {c\left( {{2m} + 1} \right)}}} \right)}}} & \left\lbrack {{Equation}\mspace{14mu} 1} \right\rbrack\end{matrix}$

In Equation, m=0, 1, . . . , 12N_(RB) ^(max,DL)−1 is defined for anormal CP and m=0, 1, . . . , 0, 1, . . . , 16N_(RB) ^(max,DL)−1 isdefined for an extended CP.

In Equation 1, a pseudo-random sequence c(i) is defined as shown inEquation 8. A pseudo-random sequence generator is initialized toc_(init) as shown in Equation 2 at the beginning of each radio frame.c _(init)=(└n _(s)/2┘+1)·(2N _(ID) ^(cell)+1)·2¹⁶ +n _(SCID)  [Equation2]

In Equation 2, n_(SCID) is basically configured to 0, and can beconfigured to a value of 0 or 1 depending on the value of a scramblingidentity field within a DCI format.

Unlike that a CRS of the legacy LTE system is used for channelmeasurement, handover measurement and data demodulation, a CSI-RS isdesigned mainly for channel measurement. The CSI-RS can also be used forhandover measurement. Since the CSI-RS is transmitted only to acquireinformation about a channel state, the CSI-RS may not be transmitted inevery subframe unlike the CRS of the legacy LTE system. Accordingly, theCSI-RS may be intermittently (e.g., periodically) transmitted in thetime domain to reduce CSI-RS overhead.

The CSI-RS can be transmitted using 1, 2, 4 or 8 antenna port, e.g.,antenna port p=15, p=15, 16, p=15, . . . , 18 and p=15, . . . , 22.

A CSI-RS sequence r_(l,n) _(s) (m) may be defined as shown in Equation3.

$\begin{matrix}{{{r_{l,n_{s}}(m)} = {{\frac{1}{\sqrt{2}}\left( {1 - {2 \cdot {c\left( {2m} \right)}}} \right)} + {j\;\frac{1}{\sqrt{2}}\left( {1 - {2 \cdot {c\left( {{2m} + 1} \right)}}} \right)}}},\mspace{20mu}{m = 0},1,\ldots\mspace{14mu},{N_{RB}^{{{ma}\; x},{DL}} - 1}} & \left\lbrack {{Equation}\mspace{14mu} 3} \right\rbrack\end{matrix}$

In Equation 3, n_(s) denotes a slot number in a radio frame, and ldenotes an OFDM symbol number in a corresponding slot. The pseudo-randomsequence c(i) is defined as shown in Equation 8. A pseudo-randomsequence generator is initialized to c_(init) as shown in Equation 4 atthe beginning of each radio frame.c _(init)=2¹⁰·(7·(n _(s)+1)+l+1)·(2·N _(ID) ^(cell)+1)+2·N _(ID) ^(cell)+N _(CP)  [Equation 4]

In Equation 4, N_(CP) is defined as 1 for a normal CP and 0 for anextended CP.

Uplink Subframe Structure

FIG. 5 is a view illustrating the structure of a UL subframe.

Referring to FIG. 5, a UL subframe can be divided into a control regionand a data region in the frequency domain. One or more Physical UplinkControl Channels (PUCCHs) can be allocated to the control region tocarry Uplink Control Information (UCI). One or more Physical UplinkShared Channels (PUSCHs) may be allocated to the data region of the ULsubframe to carry user data.

In the UL subframe, subcarriers away from a Direct Current (DC)subcarrier are used as the control region. In other words, subcarrierslocated at two ends of a UL transmission bandwidth are assigned to UCItransmission. The DC subcarrier is a remaining component not used forsignal transmission and is mapped to carrier frequency f0 duringfrequency up-conversion. A PUCCH for a single UE is allocated to an RBpair belonging to resources operating at a carrier frequency in asubframe and RBs belonging to the RB pair occupy different subcarriersin two slots. Assignment of the PUCCH in this manner is represented asfrequency hopping of an RB pair allocated to the PUCCH at a slotboundary. When frequency hopping is not used, the RB pair occupies thesame subcarrier.

The PUCCH can be used to transmit the following control information.

-   -   Scheduling Request (SR): Information used to request a UL-SCH        resource and is transmitted using On-Off Keying (OOK) scheme.    -   HARQ-ACK: Response to a PDCCH and/or a downlink data packet        (e.g., codeword) on a PDSCH and indicates whether the PDCCH or        PDSCH has been successfully received. A 1-bit HARQ-ACK signal is        transmitted as a response to a single downlink codeword and a        2-bit HARQ-ACK signal is transmitted as a response to two        downlink codewords. The HARQ-ACK response includes positive ACK        (simply, ACK), negative ACK (NACK), Discontinuous Transmission        (DTX) or NACK/DTX. Here, the term HARQ-ACK is used        interchangeably with the terms HARQ ACK/NACK and ACK/NACK.    -   Channel State Information (CSI): Feedback information about a        downlink channel. Multiple Input Multiple Output (MIMO)-related        feedback information includes a Rank Indicator (RI) and a        Precoding Matrix Indicator (PMI).

The amount of Uplink Control Information (UCI) that a UE can transmit ina subframe depends on the number of SC-FDMA symbols available forcontrol information transmission. The SC-FDMA symbols available forcontrol information transmission refer to SC-FDMA symbols other thanSC-FDMA symbols for reference signal transmission in the subframe. Inthe case of a subframe in which a Sounding Reference Signal (SRS) isconfigured, the last SC-FDMA symbol of the subframe is excluded from theSC-FDMA symbols available for control information transmission. Areference signal is used to detect coherence of the PUCCH. The PUCCHsupports various formats base on information transmitted thereon.

Briefly, PUCCH format 1 is used to transmit an SR, PUCCH format 1a/1b isused to transmit ACK/NACK information, PUCCH format 2 is used to deliverCSI such as CQI/PMI/RI, PUCCH format 2a/2b is used to deliver ACK/NACKinformation together with CSI, and PUCCH format 3 series is used totransmit ACK/NACK information

UCI Transmission

FIGS. 6 to 10 illustrate UCI transmission using PUCCH format 1 series,PUCCH format 2 series and PUCCH format 3 series.

In the 3GPP LTE/LTE-A system, a subframe having a normal CP includes 2slots each including 7 OFDM symbols (or SC-FDMA symbols). A subframehaving an extended CP includes 2 slots each including 6 OFDM symbols (orSC-FDMA symbols). Since the number of OFDM symbols (or SC-FDMA symbols)per a subframe varies depends on a CP length, a PUCCH transmissionstructure in a UL subframe varies depending on the CP length.Accordingly, a method for transmitting UCI in a UL subframe by a UEvaries depending on a PUCCH format and a CP length.

Referring to FIGS. 6 and 7, in case of transmission using PUCCH formats1a and 1b, the same control information is repeated on a slot basis in asubframe. UEs transmit ACK/NACK signals using different resources havingdifferent cyclic shifts (CSs) of a Computer-Generated Constant AmplitudeZero Auto Correlation (CG-CAZAC) sequence and an Orthogonal Cover Code(OCC). A CS may correspond to a frequency domain code and an OCC maycorrespond to a time domain spreading code. An OCC may also be referredto as an orthogonal sequence. An OCC includes, for example, aWalsh/Discrete Fourier Transform (DFT) orthogonal code. When the numberof CSs is 6 and the number of OCCs is 3, a total of 18 PUCCHs can bemultiplexed in the same Physical Resource Block (PRB) on the basis of asingle antenna port. An orthogonal sequence of w₀, w₁, w₂ and w₃ may beused in an arbitrary time domain after Fast Fourier Transform (FFT) orin an arbitrary frequency domain before FFT. A PUCCH resource forACK/NACK transmission in the 3GPP LTE/LTE-A system is represented as acombination of the position of a time-frequency resource (e.g., PRB), acyclic shift of a sequence for frequency spreading and an orthogonalcode (or quasi-orthogonal code) for time spreading. Each PUCCH resourceis indicated using a PUCCH resource index (also referred to as a PUCCHindex). A slot level structure of PUCCH format 1 series for SRtransmission is the same as that of PUCCH formats 1a and 1b while onlymodulation methods thereof are different.

FIG. 8 illustrates transmission of CSI in a UL slot having a normal CPusing PUCCH format 2a/2b/2c and FIG. 9 illustrates transmission of CSIin a UL slot having an extended CP using PUCCH format 2a/2b/2c.

Referring to FIGS. 8 and 9, in case of the normal CP, a UL subframeincludes 10 SC-FDMA symbols excluding symbols carrying UL RSs. The CSIis coded into 10 transmission symbols (also referred to ascomplex-valued modulation symbols) through block coding. The 10transmission symbols are respectively mapped to 10 SC-FDMA symbols andtransmitted to an eNB.

PUCCH format 1/1a/1b and PUCCH format 2/2a/2b can carry UCI up to acertain number of bits. However, as the amount of UCI is increased dueto use of carrier aggregation, increase in the number of antennas andadoption of a TDD system, a relay system and a multi-node system, aPUCCH format capable of carrying a larger amount of UCI than PUCCHformats 1/1a/1b/2/2a/2b has been adopted and this format is referred toas PUCCH format 3. For example, PUCCH format 3 can be used when a UE forwhich carrier aggregation is configured transmits a plurality ofACK/NACK signals in response to a plurality of PDSCHs received from aneNB through a plurality of downlink carriers, through a specific uplinkcarrier.

PUCCH format 3 may be configured based on, for example, block spreading.Referring to FIG. 10, block spreading time-domain-spreads a symbolsequence using an OCC (or orthogonal sequence) and transmits the spreadsymbol sequence. Using block spreading, control signals of a pluralityof UEs can be multiplexed to the same RB due to the OCC and transmittedto an eNB. In the case of PUCCH format 2, a symbol sequence istransmitted over the time domain, and UCI of UEs are multiplexed using aCS of a CAZAC sequence and transmitted to an eNB. On the other hand, inthe case of the new PUCCH format (e.g., PUCCH format 3) based on blockspreading, a symbol sequence is transmitted over the frequency domain,and UCI of UEs are multiplexed using OCC based time-domain spreading andtransmitted to the eNB. For example, referring to FIG. 8, a symbolsequence is spread using a length-5 (i.e., SF=5) OCC and mapped to 5SC-FDMA symbols. Although FIG. 10 illustrates a case in which a total of2 RS symbols are used in 1 slot, 3 RS symbols may be used and an OCCwith SF=4 can be used for symbol sequence spreading and UE multiplexing.Here, the RS symbols can be generated from a CAZAC sequence having aspecific CS and transmitted from the UE to the eNB after a specific OCCis applied thereto/multiplied thereby. In FIG. 10, DFT may be previouslyused prior to the OCC, and Fast Fourier Transform (FFT) may be usedinstead of DFT.

In FIGS. 6 to 10, a UL RS transmitted together with UCI on a PUCCH canbe used to demodulate the UCI by the eNB.

FIG. 11 illustrates multiplexing of UCI and uplink data in a PUSCHregion.

The uplink data can be transmitted in a data region of a UL subframethrough a PUSCH. A UL DMRS which is a reference signal for demodulationof the uplink data can be transmitted together with the uplink data inthe data region of the UL subframe. The control region and the dataregion in the UL subframe are respectively referred to as a PUCCH regionand a PUSCH region.

When UCI needs to be transmitted in a subframe to which PUSCHtransmission is assigned, as long as simultaneous transmission of thePUSCH and a PUCCH is not allowed, a UE multiplexes the UCI and uplinkdata (hereinafter referred to as PUSCH data) before DFT-spreading andtransmits the multiplexed UL signal on a PUSCH. The UCI includes atleast one of CQI/PMI, HARQ ACK/NACK and RI. The number of REs used forCQI/PMI, HARQ ACK/NACK or RI transmission is based on a Modulation andCoding Scheme (MCS) and an offset value (Δ_(offset) ^(CQI), Δ_(offset)^(HARQ-ACK), Δ_(offset) ^(RI)) allocated for PUSCH transmission. Theoffset value allows different coding rates based on the UCI and issemi-statically configured through higher layer (e.g., Radio ResourceControl (RRC)) signaling. The PUSCH data and the UCI are not mapped tothe same RE. The UCI is mapped to be present in both slots of thesubframe.

Referring to FIG. 11, CQI and/or PMI resources are located at the startof PUSCH data resources and sequentially mapped to all SC-FDMA symbolsin a subcarrier and then to a next subcarrier. The CQI/PMI is mappedfrom left to right within a subcarrier, i.e., in a direction in whichthe SC-FDMA symbol index increases. The PUSCH data is rate-matched inconsideration of the amount of CQI/PMI resources (i.e., the number ofcoded symbols). The same modulation order as that of UL-SCH data is usedfor the CQI/PMI. An ACK/NACK signal is punctured into a part of SC-FDMAresources to which the UL-SCH data is mapped. The ACK/NACK signal islocated adjacent to a PUSCH RS which is a reference signal fordemodulation of the PUSCH data, and is filled from bottom to top withincorresponding SC-FDMA symbols, i.e., in a direction in which thesubcarrier index increases. In the case of a normal CP, SC-FDMA symbolsfor the ACK/NACK signal are located at SC-FDMA symbols #2/#5 in eachslot as illustrated in FIG. 11. The coded RI is located adjacent to thesymbols for the ACK/NACK signal irrespective of whether the ACK/NACKsignal is actually transmitted in the subframe.

In 3GPP LTE, UCI may be scheduled to be transmitted on a PUSCH withoutPUSCH data. Multiplexing of ACK/NACK, RI and CQI/PMI is similar to thatillustrated in FIG. 11. Channel coding and rate matching for controlsignaling without PUSCH data are the same as those for control signalingwith PUSCH data, which are described above.

In FIG. 11, the PUSCH RS can be used to demodulate the UCI and/or thePUSCH data transmitted in the PUSCH region. In the present invention, aUL RS associated with PUCCH transmission and a PUSCH RS associated withPUSCH transmission are collectively referred to as a DMRS.

A Sounding Reference Signal (SRS) (not shown) may be allocated to thePUSCH region. The SRS is a UL RS not associated with transmission of aPUSCH or PUCCH. The SRS is transmitted on the last SC-FDMA symbol of aUL subframe in the time domain and in a data transmission band, i.e., aPUSCH region, of the UL subframe in the frequency domain. An eNB canmeasure an uplink channel state between a UE and the eNB using the SRS.SRSs of a plurality of UEs, which are transmitted/received on the lastSC-FDMA symbol of the same subframe, can be distinguished depending onfrequency positions/sequences thereof.

Uplink Reference Signal

A DM RS transmitted in a PUCCH region and a DM RS and an SRS transmittedin a PUSCH region are UE-specifically generated by a specific UE andtransmitted to an eNB and thus can be regarded as uplink UE-specificRSs.

A UL RS is defined based on a cyclic shift of a base sequence accordingto a predetermined rule. For example, an RS sequence r_(u,v) ^((α))(n)is defined based on a cyclic shift α of a base sequence r_(u,v)(n) asshown in Equation 5.r _(u,v) ^((α))(n)=e _(jαn) ·r _(u,v)(n),0≤n<M _(sc) ^(RS)  [Equation 5]

Here, M_(sc) ^(RS) denotes the length of an RS sequence, M_(sc)^(RS)=m·N_(sc) ^(RB) and 1≤m≤N_(RB) ^(max,UL), N_(RB) ^(max,UL)represented as a multiple of N_(sc) ^(RB) by an integer denotes thelargest uplink bandwidth configuration. N_(sc) ^(RB) denotes the size ofan RB and is represented as the number of subcarriers. A plurality of RSsequences can be defined from a base sequence through different cyclicshift values α. A plurality of base sequences is defined for a DM RS andan SRS. For example, the base sequences may be defined using a rootZadoff-Chu sequence. Base sequences r_(u,v)(n) are divided into groupseach including one or more base sequences. For example, each basesequence group can include one base sequence (v=0) having a length ofM_(sc) ^(RS)=m·N_(sc) ^(RB) (1≤m≤5) and two base sequences having alength of M_(sc) ^(RS)=m·N_(sc) ^(RB) (6≤m≤N_(sc) ^(RB)). In r_(u,v)(n),uϵ{0, 1, . . . , 29} denotes a group number (i.e., group index) and vdenotes a base sequence number (i.e., base sequence index) in acorresponding group. Each of the base sequence group number and the basesequence number in the corresponding group may vary upon time.

The sequence group number u in slot n_(s) is defined based on a grouphopping pattern f_(gh)(n_(s)) and a sequence shift pattern f_(ss) asshown in Equation 6.ιl=f _(gh)(n _(s))+f _(ss))mod 30  [Equation 6]

In Equation 6, mod denotes a modulo operation, and A mod B denotes aremainder obtained by dividing A by B.

There are a plurality of different hopping patterns (e.g., 30 hoppingpatterns) and a plurality of different sequence shift patterns (e.g., 17sequence shift patterns).

Sequence group hopping may be enabled or disabled by a cell-specificparameter given from a higher layer.

The group hopping pattern f_(gh)(n_(s)) for a PUSCH and a PUCCH may begiven as shown in Equation 7.

$\begin{matrix}{{f_{gh}\left( n_{s} \right)} = \left\{ \begin{matrix}0 & {{if}\mspace{14mu}{group}\mspace{14mu}{hopping}\mspace{14mu}{is}\mspace{14mu}{disabled}} \\{\left( {\sum\limits_{i = 0}^{7}{{c\left( {{8n_{s}} + i} \right)} \cdot 2^{i}}} \right){mod}\; 30} & {{if}\mspace{14mu}{group}\mspace{14mu}{hopping}\mspace{14mu}{is}\mspace{14mu}{enabled}}\end{matrix} \right.} & \left\lbrack {{Equation}\mspace{14mu} 7} \right\rbrack\end{matrix}$

Here, a pseudo-random sequence c(i) can be defined based on a length-31gold sequence. An output sequence c(n) (n=0, 1, . . . , M_(PN)−1) havinga length of M_(PN) is defined as shown in Equation 8.c(n)=(x ₁(n+N _(C))+x ₂(n+N _(C)))mod 2x ₁(n+31)=(x ₁(n+3)+x ₁(n))mod 2x ₂(n+31)=(x ₂(n+3)+x ₂(n+2)+x ₂(n+1)+x ₂(n))mod 2  [Equation 8]

Here, N_(C)=1600 and a first m-sequence is initialized to x₁(0)=1,x₁(n)=0, n=1, 2, . . . , 30. Initialization of a second m-sequence isrepresented as shown in Equation 9 having a value which is dependentupon application of the sequence.c _(init)=Σ_(i=0) ³⁰ x ₂(i)·2^(i)  [Equation 9]

In Equation 7, a pseudo-random sequence generator is initialized toc_(init) as shown in Equation 10 at the beginning of each radio frame.

$\begin{matrix}{c_{init} = \left\lfloor \frac{N_{ID}^{cell}}{30} \right\rfloor} & \left\lbrack {{Equation}\mspace{14mu} 10} \right\rbrack\end{matrix}$

In Equation 10, └ ┘ denotes a floor operation and └A┘ is a maximuminteger less than or equal to A.

According to the current 3GPP LTE(−A) standard, a PUCCH and a PUSCH havethe same group hopping pattern as shown in Equation 7 but have differentsequence shift patterns. A sequence shift pattern f_(ss) ^(PUCCH) forthe PUCCH is given based on cell identity (cell ID) as shown in Equation11.f _(ss) ^(PUCCH) =N _(ID) ^(cell) mod 30  [Equation 11]

A sequence shift pattern f_(ss) ^(PUSCH) for the PUSCH is given as shownin Equation 12 using the sequence shift pattern f_(ss) ^(PUCCH) for thePUCCH and a value Δ_(ss) configured by a higher layer.f _(ss) ^(PUSCH)=(f _(ss) ^(PUCCH)+Δ_(ss))mod 30  [Equation 12]

Here, Δ_(ss)ϵ{0, 1, . . . , 29}.

Base sequence hopping is applied only to RSs having a length of M_(sc)^(RS)≥6N_(sc) ^(RB). For RSs having a length of M_(sc) ^(RS)<6N_(sc)^(RB), a base sequence number v in a base sequence group is given asv=0. For the RSs having a length of M_(sc) ^(RS)≥6N_(sc) ^(RB), the basesequence number v in a base sequence group in slot n_(s) is defined asv=c(n_(s)) if group hopping is disabled and sequence hopping is enabled,and defined as v=0 otherwise. Here, a pseudo-random sequence c(i) isgiven as shown in Equation 8. A pseudo-random sequence generator isinitialized to c_(init) as shown in Equation 13 at the beginning of eachradio frame.

$\begin{matrix}{c_{init} = {{\left\lfloor \frac{N_{ID}^{cell}}{30} \right\rfloor \cdot 2^{5}} + f_{ss}^{PUSCH}}} & \left\lbrack {{Equation}\mspace{11mu} 13} \right\rbrack\end{matrix}$

A sequence r_(PUCCH) ^((p))(⋅) of a UL RS (hereinafter referred to as aPUCCH DM RS) in FIGS. 6 to 10 is given as shown in Equation 14.

$\begin{matrix}{{r_{PUCCH}^{(p)}\left( {{m^{\prime}N_{RS}^{PUCCH}M_{sc}^{RS}} + {mM}_{sc}^{RS} + n} \right)} = {\frac{1}{\sqrt{P}}{{\overset{\_}{w}}^{(p)}(m)}{z(m)}{r_{u,v}^{({\alpha\;\_\; p})}(n)}}} & \left\lbrack {{Equation}\mspace{14mu} 14} \right\rbrack\end{matrix}$

Here, m=0, . . . , N_(RS) ^(PUCCH)−1, n=0, . . . , M_(sc) ^(RS)−1, andm′=0, 1. N_(RS) ^(PUCCH) denotes the number of reference symbols per aslot for the PUCCH and P denotes the number of antenna ports used forPUCCH transmission. A sequence r_(u,v) ^((α) ^(_) ^(p))(n) is given asshown in Equation 5 having M_(sc) ^(RS)=12, and a cyclic shift α_p isdetermined based on a PUCCH format.

All PUCCH formats use a cell-specific CS, n_(cs) ^(cell)(n_(s),l).n_(cs) ^(cell)(n_(s),l) has a value based on a symbol number l and aslot number n_(s) and is determined as n_(cs) ^(cell)(n_(s),l)=Σ_(i=0)⁷c(8N_(symb) ^(UL)·n_(s)+8l+i)·2^(i). Here, a pseudo-random sequencec(i) is initialized to c_(init)=N_(ID) ^(cell) at the beginning of eachradio frame.

For PUCCH formats 2a and 2B, z(m) is the same as d(10) if m=1, andz(m)=1 otherwise. For PUCCH formats 2a and 2b supported for a normal CPonly, UCI information bits b(20), . . . , b(M_(bit)−1) among b(0), . . ., b(M_(bit)−1) are modulated into a single modulation symbol d(10) usedto generate a reference signal for PUCCH formats 2a and 2b, as shown inTable 1.

TABLE 1 PUCCH format b(20), . . . ,b(M_(bit)−1) d(10) 2a 0 1 1 −1  2b 001 01 −j  10 j 11 −1 

The PUSCH RS (hereinafter referred to as a PUSCH DM RS) of FIG. 11 istransmitted on a layer basis. A PUSCH DM RS sequence r_(PUSCH) ^((p))(⋅)associated with layer λϵ{0, 1, . . . , ν−1} is given as shown inEquation 15.r _(PUSCH) ^((λ))(m·M _(sc) ^(RS) +n)=w ^((λ))(m)r _(u,v) ^((α) ^(_)^(λ))(n)  [Equation 15]

Here, m=0, 1, n=, . . . , M_(sc) ^(RS)−1, and M_(sc) ^(RS)=M_(sc)^(PUSCH). M_(sc) ^(PUSCH) is a bandwidth scheduled for uplinktransmission and denotes the number of subcarriers. An orthogonalsequence w^((λ))(m) can be given as shown in Table 2 using a cyclicshift field in the most recent uplink-related DCI for transport blocksassociated with corresponding PUSCH transmission. Table 2 shows mappingof the cyclic shift field in the uplink-related DCI format to n_(DMRS,λ)⁽²⁾ and [w^((λ))(0) w^((λ))(1)].

TABLE 2 Cyclic Shift Field in uplink-related DCI format n_(DMRS, λ) ⁽²⁾[w^((λ))(0) w^((λ))(1)] λ = 0 λ = 1 λ = 2 λ = 3 λ = 0 λ = 1 λ = 2 λ = 3000 0 6 3 9 [1 1] [1 1] [1 −1] [1 −1] 001 6 0 9 3 [1 −1] [1 −1] [1 1] [11] 010 3 9 6 0 [1 −1] [1 −1] [1 1] [1 1] 011 4 10 7 1 [1 1] [1 1] [1 1][1 1] 100 2 8 5 11 [1 1] [1 1] [1 1] [1 1] 101 8 2 11 5 [1 −1] [1 −1] [1−1] [1 −1] 110 10 4 1 7 [1 −1] [1 −1] [1 −1] [1 −1] 111 9 3 0 6 [1 1] [11] [1 −1] [1 −1]

A cyclic shift α_λ in slot n_(s) is given as 2πn_(cs,λ)/12. Here,n_(cs,λ)=(n_(DMRS) ⁽¹⁾+n_(DMRS,λ) ⁽²⁾+n_(PN)(n_(s)))mod 12. n_(DMRS) ⁽¹⁾is given as shown in Table 3 based on a cyclic shift parameter giventhrough higher layer signaling. Table 3 shows mapping of cyclic shiftsto n_(DMRS) ⁽¹⁾ through higher layer signaling.

TABLE 3 cyclic Shift n_(DMRS) ⁽¹⁾ 0 0 1 2 2 3 3 4 4 6 5 8 6 9 7 10

Moreover, n_(PN)(n_(s)) is given as shown in Equation 16 using acell-specific pseudo-random sequence c(i).n _(PN)(n _(s))=Σ_(i=0) ⁷ c(8N _(symb) ^(UL) ·n _(s)+i)·2^(i)  [Equation 16]

Here, the pseudo-random sequence c(i) is defined as shown in Equation 8.A pseudo-random sequence generator is initialized to c_(init) as shownin Equation 17 at the beginning of each radio frame.

$\begin{matrix}{c_{init} = {{\left\lfloor \frac{N_{ID}^{cell}}{30} \right\rfloor \cdot 2^{5}} + f_{ss}^{PUSCH}}} & \left\lbrack {{Equation}\mspace{14mu} 17} \right\rbrack\end{matrix}$

An SRS sequence r_(SRS) ^((p))(n)=r_(u,v) ^((α) ^(_) ^(p))(n) is definedas shown in Equation 5. Here, u denotes the PUCCH sequence group numberdescribed above in relation to group hopping and v denotes the basesequence number described above in relation to sequence hopping. Acyclic shift α_p of the SRS is given as shown in Equation 18.

$\begin{matrix}{{{\alpha_{p} = {2\pi\;\frac{n_{SRS}^{{cs},p}}{8}}}n_{SRS}^{{cs},p} = {\left( {n_{SRS}^{cs} + \frac{8p}{N_{ap}}} \right){mod}\; 8}}{p \in \left\{ {0,1,\ldots\mspace{14mu},{N_{ap} - 1}} \right\}}} & \left\lbrack {{Equation}\mspace{14mu} 18} \right\rbrack\end{matrix}$

Here, n_(SRS) ^(cs)={0, 1, 2, 3, 4, 5, 6, 7} is a value configured foreach UE by higher layer parameters and configured by different higherlayer parameters for periodic sounding and aperiodic soundingconfigurations. N_(ap) denotes the number of antenna ports used for SRStransmission.

Coordinated Multi-Point (CoMP)

A CoMP transmission/reception scheme (also referred to as co-MIMO,collaborative MIMO or network MIMO) is proposed to meet enhanced systemperformance requirements of 3GPP LTE-A. CoMP can improve the performanceof a UE located at a cell edge and increase an average sectorthroughput.

Generally, in a multi-cell environment having a frequency reuse factorof 1, the performance of a UE located at a cell edge and an averagesector throughput may decrease due to inter-cell interference (ICI). Toreduce ICI, the legacy LTE system uses a method for providing anappropriate throughput performance to a UE located at a cell edge in anenvironment restricted by interference, simply using a passive schemesuch as fractional frequency reuse (FFR) through UE-specific powercontrol. However, it may be more preferable to reduce ICI or reuse ICIas a signal desired by a UE rather than decreasing use of frequencyresources per a cell. To achieve this, a CoMP transmission scheme can beused.

A CoMP scheme applicable to downlink can be largely classified intoJoint Processing (JP) and Coordinated Scheduling/Coordinated Beamforming(CS/CB).

According to the JP scheme, each point (BS) of a CoMP coordination unitcan use data. The CoMP coordination unit refers to a set of BSs used fora coordinated transmission scheme. The JP scheme can be classified intojoint transmission and dynamic cell selection.

The joint transmission scheme refers to a scheme for transmitting PDSCHssimultaneously from a plurality of points (a part of or the whole CoMPcoordination unit). That is, data directed to a single UE can betransmitted simultaneously from a plurality of transmission points.According to the joint transmission scheme, the quality of a receivedsignal can be improved coherently or non-coherently and interference onother UEs can be actively eliminated.

The dynamic cell selection scheme refers to a scheme for transmitting aPDSCH from one point (of a CoMP coordination unit) at a time. That is,data directed to a single UE at a specific time is transmitted from onepoint and other points in the coordination unit do not transmit data tothe UE at that time. The point which transmits the data to the UE can bedynamically selected.

According to the CS/CB scheme, CoMP coordination units can cooperativelyperform beamforming of data transmission to a single UE. Here, data istransmitted only from a serving cell but user scheduling/beaming can bedetermined through coordination of cells of a corresponding CoMPcoordination unit.

In case of uplink, coordinated multi-point reception refers to receptionof a signal transmitted through coordination of a plurality of pointsgeographically spaced apart from each other. A CoMP scheme applicable touplink can be classified into Joint Reception (JR) and CoordinatedScheduling/Coordinated Beamforming (CS/CB).

The JR scheme refers to a scheme for receiving a PUSCH signal by aplurality of reception points and the CS/CB scheme refers to a schemefor receiving a PUSCH signal by a single point but determining userscheduling/beamforming through coordination of cells of a CoMPcoordination unit.

Using a CoMP system, a UE can receive data cooperatively from multi-cellBSs. The BSs can simultaneously support one or more UEs using the sameradio frequency resource to improve system performance. Moreover, a BSmay perform Space Division Multiple Access (SDMA) based on CSI betweenthe BS and a UE.

In the CoMP system, a serving BS and one or more cooperative BSs areconnected to a scheduler through a backbone network. The scheduler canoperate by receiving channel information about a channel state betweeneach UE and each cooperative BS, which is measured by and fed back fromeach BS, through the backbone network. For example, the scheduler canschedule information for a collaborative MIMO operation of the servingBS and the cooperative BSs. That is, the scheduler can directly give aninstruction about a collaborative MIMO operation to each BS.

As described above, the CoMP system can be regarded as a virtual MIMOsystem of a group of a plurality of cells. Basically, a communicationscheme of MIMO using multiple antennas can be applied to CoMP.

Enhanced Reference Signal Transmission/Reception Scheme

Referring to Equations 5 to 18, UEs located in a cell initializepseudo-random sequence generator for generating RS sequences, using thesame N_(ID) ^(cell). Since a single UE transmits an uplink signal onlyto one cell in view of the UE, the UE uses only one N_(ID) ^(cell) togenerate a PUSCH DM RS, a PUCCH DM RS and an SRS. That is, in a legacysystem in which a UE transmits an uplink signal only to one cell, a UEbased DM RS sequence was used. In other words, since the legacycommunication system performs uplink transmission only for one cell, aUE can acquire N_(ID) ^(cell) (i.e., physical layer cell ID) based on adownlink Primary Synchronization Signal (PSS) and a SecondarySynchronization Signal (SSS) received from a serving cell and use theacquired N_(ID) ^(cell) to generate an uplink RS sequence.

However, in uplink CoMP, a UE can transmit an uplink signal to all or apart of a plurality of cells or reception points (RPs). In this case, ifan uplink transmitter transmits an RS sequence generated using a legacymethod, a receiver may not detect the RS sequence.

Accordingly, for CoMP by which a plurality of cells or RPs participatein communication with a UE, DM RS generation, resource allocation and/ortransmission schemes for data transmitted to different points need to bedefined even when the different points do not simultaneously receive thedata. One RP can receive an uplink signal from a UE through one or morecells. However, for convenience of explanation, cells for receiving anuplink signal are collectively referred to as an RP in the followingdescription.

The present invention proposes a method for generating an RS sequenceused for PUSCH transmission, PUCCH transmission and/or SRS transmissionby a CoMP UE in a multi-cell (multi-RP) environment.

FIG. 12 is a view for describing an exemplary UL CoMP operation.

In an uplink CoMP operation by which one UE (i.e., CoMP UE) transmits aPUSCH to a plurality of cells (or RPs), it is important to ensure mutualorthogonality among uplink DMRSs. If mutual orthogonality among uplinkDMRSs is not ensured, each RP cannot correctly estimate an uplinkchannel and thus PUSCH demodulation performance can be greatly reduced.Basically, the UE can generate a base sequence of DMRS using a cell IDof a serving cell and apply an OCC for orthogonality with other DMRSs asnecessary. Specifically, a base sequence of uplink DMRS should bedetermined as a function of the cell ID, and a base sequence index ofPUSCH DMRS is determined to have an offset of Δ_(ss) relatively from abase sequence index of PUCCH DMRS. In this case, Δ_(ss) is given throughhigher layer signaling (e.g., RRC signaling). That is, the same cell IDis used to generate base sequences of the PUCCH DMRS and the PUSCH DMRSand a base sequence index offset of Δ_(ss) is applied therebetween (seeEquation 12). For example, if Δ_(ss)=0 is given through RRC signaling,the PUCCH DMRS and the PUSCH DMRS may be determined to have the samebase sequence.

Since the CoMP UE can have different DL and UL serving cells, the cellID of the DL serving cell cannot be equally used to generate a UL DMRSbase sequence and the UL DMRS base sequence needs to be generated usinga cell ID of an RP based on decision of a scheduler. That is, the ULDMRS base sequence should be generated using an ID of a cell other thana serving cell. To provide enough scheduling flexibility in determiningUEs paired for MU-MIMO, it is desirable to dynamically indicate a cellID used to generate a UL DMRS. For example, a higher layer can signal aplurality of DMRS configurations (including a DMRS configuration forcell A and a DMRS configuration for cell B) to a CoMP UE located atedges of cell A and cell B in FIG. 12. The CoMP UE may be co-scheduledwith another UE (UE-A) of cell A or another UE (UE-B) of cell Baccording to channel conditions and/or other network side conditions.That is, a DMRS base sequence of the CoMP UE can be generated using anID of a cell to which a UE co-scheduled with the CoMP UE belongs. Thecell ID used to generate the DMRS base sequence can be dynamicallyselected or indicated.

Referring to Equations 1 to 4, UEs located in a cell can receive an RS(e.g., CSI-RS or UE-specific RS) sequence generated by a pseudo-randomsequence generator initialized using the same N_(ID) ^(cell), from a BS.That is, in a legacy system in which a UE receives a downlink signalfrom one cell, a Physical layer Cell ID (PCI) may be used to generate adownlink sequence.

However, in downlink CoMP, a UE can receive a downlink signal from allor a part of a plurality of cells or transmission points (TPs). In thiscase, if a downlink transmitter transmits an RS sequence generated usinga legacy method, a receiver (i.e., UE) may not detect the RS sequence.

Accordingly, for CoMP by which a plurality of cells or RPs participatein communication with a UE, CSI-RS and UE-specific RS generation,resource allocation and/or transmission schemes for channels fromdifferent points need to be defined even when the different points donot simultaneously transmit data. As such, a method for correctlyreceiving a CSI-RS and a UE-specific RS and performing CSI generationand PDSCH demodulation by a UE in DL CoMP needs to be defined.

In the present invention, a cell ID to be used to generate an RS basesequence may be provided to a UE to support the above-describeduplink/downlink CoMP operation. In this case, the cell ID used togenerate an RS base sequence may be represented using a parameter suchas n_(ID) to be distinguished from N_(ID) ^(cell) which is a parameterindicating a cell ID (i.e., PCI) used to generate a sequence of varioustypes of RSs (i.e., UL RSs (e.g., PUSCH DMRS, PUCCH DMRS and SRS) and/orDL RSs (e.g., CSI-RS and UE-specific RS)) in a legacy operation. Here,n_(ID) may also be referred to as a Virtual Cell ID (VCI) for generatinga UL/DL RS sequence. Basically, the VCI may have the same value as PCI,or may be configured to a different value from the PCI.

Further, a parameter (e.g., Δ_(ss)) associated withgeneration/transmission of an RS may be signaled to a UE in addition tothe VCI used to generate a base sequence of various types of RSs. In thepresent specification, the VCI and the related parameter(s) are referredto as an RS parameter set. In addition, the RS parameter set may beconfigured for a UE per an RS type or per a group of RS types. Besides,one or more RS parameter sets may be signaled for a single RS type or RStype group.

The RS parameter set for a certain RS type or RS type group may beexplicitly signaled, or implicitly signaled based on configuration of anRS parameter set for another RS type or RS type group. To signal the RSparameter set, UE-specific higher layer signaling (e.g., RRC signaling)and/or dynamic signaling using DCI may be used.

A description is now given of embodiments of the above-describedproposal of the present invention.

Configuration of RS Parameter Set for UL RS

A description is now given of a method for configuring an RS parameterset for a UL RS (i.e., PUSCH DMRS, PUCCH DMRS or SRS).

An individual RS parameter set may be basically configured per a UL RStype, but this may increase signaling overhead. Accordingly, the presentinvention proposes to define an RS parameter set commonly applied to RStypes for repeated parts among parameter sets applied to the RS types.Further, RS parameter sets applied to individual RS types may beadditionally defined. The common RS parameter set and the individual RSparameter sets may be signaled, and rules to which the common RSparameter set is applied and rules to which the individual RS parametersets are applied may be additionally defined.

Embodiment 1

As described above, according to the proposal of the present invention,a VCI is used to determine a base sequence index of a specific type RS.The current embodiment proposes a method for configuring a VCI to thesame value as a PCI (i.e., a PCI of a serving cell) and signaling one ormore of Δ_(ss) ^(PUSCH) ^(_) ^(UE)(s), Δ_(ss) ^(PUCCH) ^(_) ^(UE)(s) andΔ_(ss) ^(SRS) ^(_) ^(UE)(s) for determining a sequence shift patternf_(ss) per an RS type through UE-specific RRC signaling.

Embodiment 1-A

The VCI is given as the PCI of the serving cell and thus does not needto be separately signaled. As such, a UE may generate an RS basesequence using the PCI of the serving cell and the other signaledparameters (Δ^(PUSCH) ^(_) ^(UE)(s), Δ_(ss) ^(PUCCH) ^(_) ^(UE)(s) orΔ_(ss) ^(SRS) ^(_) ^(UE)(s)). That is, this corresponds to a case inwhich the common RS parameter is the VCI (=the PCI of the serving cell)and the individual RS parameter is Δ_(ss).

For example, the UE may receive parameters of {Δ_(ss) ^(PUSCH) ^(_)^(UE)(0), Δ_(ss) ^(PUSCH) ^(_) ^(UE)(1), . . . , Δ_(ss) ^(PUSCH) ^(_)^(UE)(L−1), Δ_(ss) ^(PUCCH) ^(_) ^(UE)(0), Δ_(ss) ^(PUCCH) ^(_)^(UE)(1), . . . , Δ_(ss) ^(PUCCH) ^(_) ^(UE)(M−1), Δ_(ss) ^(SRS) ^(_)^(UE)(0), Δ_(ss) ^(SRS) ^(_) ^(UE)(1), . . . , Δ_(ss) ^(SRS) ^(_)^(UE)(N−1)} through UE-dedicated RRC signaling. In this case, L, M and Nare positive integers. L may correspond to the number of RPs (i.e.,PUSCH target RPs) to which a PUSCH is transmitted. Descriptions ofembodiments about M (i.e., the number of Δ_(ss) parameters applied to aPUCCH DMRS) and N (i.e., the number of Δ_(ss) parameters applied to anSRS) will be given below.

Embodiment 1-A-i

M may refer to a total number of available PUCCH formats. As such, in ULCoMP, a PUCCH can be transmitted to a different RP per a PUCCH format.That is, although the same VCI (e.g., the PCI of the serving cell) isused, if Δ_(ss) of the PUCCH DMRS is given as different values,different base sequences are eventually generated. The different basesequences may mean that the PUCCH is transmitted to different RPs. Sincea transmission structure differs per a PUCCH format (see FIGS. 6 to 10),a specific RP may process a specific PUCCH format. Further, PUCCHformats having similar characteristics may be grouped and the individualRS parameter (i.e., Δ_(ss) in the current embodiment) may be configuredper a PUCCH format group. When the PUCCH format group is configured, thesame common parameter may be configured for a PUCCH format(s) belongingto one PUCCH format group. As an RS parameter assignment unit, the PUCCHformat group may be configured as described below.

For example, Δ_(ss) ^(PUCCH) ^(_) ^(UE)(0) may correspond to PUCCHformat 1/1a/1b, Δ_(ss) ^(PUCCH) ^(_) ^(UE)(1) may correspond to PUCCHformat 2/2a/2b, and Δ_(ss) ^(PUCCH) ^(_) ^(UE)(2) may correspond toPUCCH format 3.

Further, the PUCCH formats may be subdivided to configure an RSparameter set for M=3 or above. For example, different Δ_(ss) ^(PUCCH)^(_) ^(UE) values may be assigned to PUCCH format 1 and PUCCH format1a/1b.

Alternatively, a common Δ_(ss) ^(PUCCH) ^(_) ^(UE)(m) value may beconfigured for specific PUCCH formats. For example, one Δ_(ss) ^(PUCCH)^(_) ^(UE)(m) value may be commonly assigned to dynamic PUCCH formats1a/1b and 3, and another Δ_(ss) ^(PUCCH) ^(_) ^(UE)(m′) value may becommonly assigned to semi-static PUCCH formats 1a/1b and 2/2a/2b. Here,the dynamic PUCCH format refers to a PUCCH format used for ACK/NACKtransmission in response to dynamically scheduled downlink transmission,and the semi-static PUCCH format refers to PUCCH format 1a/1b used forACK/NACK transmission in response to downlink transmissionsemi-statically scheduled. In addition, another Δ_(ss) ^(PUCCH) ^(_)^(UE)(m″) value may be commonly assigned to PUCCH format 1a/1b triggeredby an ePDCCH. Here, the ePDCCH triggered PUCCH format refers to a PUCCHformat used for ACK/NACK transmission in response to downlinktransmission scheduled by an ePDCCH (when a PDCCH transmitted in thecontrol region of FIG. 3 is called a legacy PDCCH, the ePDCCH refers toan enhanced PDCCH transmittable in the data region of FIG. 3).

Embodiment 1-A-i′

In the above embodiments, since the VCI is configured as a commonparameter to the same value as the PCI of the serving cell, a method fornot signaling the VCI but signaling Δ_(ss) has been described. However,when a method for integrating a combination (or tie) of PCI and Δ_(ss)^(PUCCH) ^(_) ^(UE)(m) into a single parameter VCI_PUCCH_(m) (e.g.,ranging from 0 to 503) is used as in the following proposal of thepresent invention (e.g., Embodiment 2 or Embodiment 7), an RS parameterset per a PUCCH format or a PUCCH format group may be assigned asdescribed below.

For example, RS parameters may be configured in such a manner thatVCI_PUCCH_(m) corresponds to PUCCH format 1/1a/1b, VCI_PUCCH_(m′)corresponds to PUCCH format 2/2a/2b, and VCI_PUCCH_(m″) corresponds toPUCCH format 3. Further, the PUCCH formats may be subdivided and thus,for example, different VCI_PUCCH_(m) values may be assigned to PUCCHformat 1 and PUCCH format 1a/1b.

Alternatively, VCI_PUCCH_(m) may be separately assigned only to dynamicPUCCH format 1/1a/1b and/or semi-static PUCCH format 1/1a/1b, andanother VCI_PUCCH_(m′) may be commonly assigned to the other PUCCHformats (e.g., PUCCH format 2/2a/2b, dynamic PUCCH format 3 and/orsemi-static PUCCH format 3).

Otherwise, VCI_PUCCH_(m) may be separately assigned only to dynamicPUCCH format 1/1a/1b/3 and/or dynamic PUCCH format 3 triggered by aPDCCH (e.g., legacy PDCCH and/or ePDCCH) received in a Common SearchSpace (CSS), and another VCI_PUCCH_(m′) may be commonly assigned to theother PUCCH formats. Here, the other PUCCH formats may include dynamicPUCCH format 1/1a/1b/3 and/or dynamic PUCCH format 3, PUCCH format2/2a/2b, semi-static PUCCH format, etc. triggered by a PDCCH (e.g.,legacy PDCCH and/or ePDCCH) received in a UE-specific Search Space(USS).

Further, one VCI_PUCCH_(m) value may be commonly assigned to dynamicPUCCH formats 1a/1b and 3, and another VCI_PUCCH_(m′) value may becommonly assigned to semi-static PUCCH formats 1a/1b and 2/2a/2b. Inaddition, another Δ_(ss) ^(PUCCH) ^(_) ^(UE)(m″) value may be commonlyassigned to PUCCH format 1a/1b and/or PUCCH format 3 triggered by anePDCCH.

Alternatively, one VCI_PUCCH_(m) value may be commonly assigned todynamic PUCCH format 1a/1b and dynamic PUCCH format 3, and anotherVCI_PUCCH_(m′) value may be commonly assigned to semi-static PUCCHformat 1a/1b, PUCCH format 2/2a/2b and semi-static PUCCH format 3. Here,semi-static PUCCH format 3 may include a case in which the capacity ofPUCCH format 3 usable to, for example, multiplex CSI is used for anothersemi-static PUCCH format.

Otherwise, one VCI_PUCCH_(m) value may be commonly assigned to dynamicPUCCH format 1a/1b, another VCI_PUCCH_(m′) value may be assigned todynamic PUCCH format 3, and another VCI_PUCCH_(m″) value may be commonlyassigned to semi-static PUCCH format 1a/1b, PUCCH format 2/2a/2b andsemi-static PUCCH format 3. Here, resources to which PUCCH format 3 ismapped may be indicated by an ACK/NACK Resource Indicator (ARI) includedin a PDCCH DCI format, and VCI_PUCCH assigned to dynamic PUCCH format 3may be further subdivided. For example, the above VCI_PUCCH_(m′) valuemay be commonly assigned to or individual VCI_PUCCH_ARI(n) may beassigned to different ARI values indicating the resources of PUCCHformat 3.

Although a common VCI (or a VCI configured to the same value as a PCI ofa serving cell) is applied to all PUCCH formats in the abovedescription, the PCI of the serving cell may be applied only to aspecific PUCCH format group (e.g., dynamic PUCCH format 1a/1b,semi-static PUCCH format 1a/1b, dynamic PUCCH format 3 and/orsemi-static PUCCH format 3). For example, a specific VCI (or a VCIconfigured to the same value as a PCI of a serving cell) may be fixed todynamic PUCCH format 1a/1b and/or PUCCH format 3 triggered by a legacyPDCCH, and another VCI may be commonly configured for the other PUCCHformats (e.g., semi-static PUCCH format 1a/1b, semi-static PUCCH format3 and/or PUCCH format 2/2a/2b) and dynamic PUCCH format 1a/1b and/ordynamic PUCCH format 3 triggered by an ePDCCH.

Embodiment 1-A-ii

M may refer to the number of PUCCH target RPs. As such, a PUCCH can betransmitted per a target RP.

Here, L may be restricted to LM. Since L corresponds to the number ofPUSCH target RPs and M corresponds to the number of PUCCH target RPs asdescribed above, the number of PUSCH target RPs may be restricted to beequal to or greater than the number of PUCCH target RPs.

Further, when RS parameters include Δ_(ss) ^(PUCCH), all of M Δ_(ss)^(PUCCH) ^(_) ^(UE) values may be restricted to be a subset of L Δ_(ss)^(PUSCH) ^(_) ^(UE) values (including a case in which M Δ_(ss) ^(PUCCH)^(_) ^(UE) values are the same as L Δ_(ss) ^(PUSCH) ^(_) ^(UE) values).This provides more flexible target RP configuration to a PUSCH foruplink data transmission compared to a PUCCH for UCI transmission. Inother words, an uplink CoMP RP set of the PUCCH may be selected as asubset of an uplink CoMP RP set of the PUSCH.

Alternatively, all of M Δ_(ss) ^(PUCCH) ^(_) ^(UE) values may beconfigured to have exactly the same values as all or a part of L Δ_(ss)^(PUSCH) ^(_) ^(UE) values in one to one manner. For example, Δ_(ss)^(PUSCH) ^(_) ^(UE)(0)=Δ_(ss) ^(PUCCH) ^(_) ^(UE)(0), Δ_(ss) ^(PUSCH)^(_) ^(UE)(1)=Δ_(ss) ^(PUCCH) ^(_) ^(UE)(1), . . . , Δ_(ss) ^(PUSCH)^(_) ^(UE)(M−1)=Δ_(ss) ^(PUCCH) ^(_) ^(UE)(M−1) may be configured.

As described above, if parameter sets of different RS types (e.g., PUSCHDMRS and PUCCH DMRS) are repeated partially or entirely, the parametersets for the RS types do not need to be separately signaled and thussignaling of the RS parameter set for any one RS type may be omitted. Inthis case, the not-signaled parameter set of the RS type (e.g., PUCCHDMRS) may be implicitly determined using a mapping relationship based onthe signaled parameter set of the RS type (e.g., PUSCH DMRS). Themapping relationship may be pre-defined or may be separately signaledfrom an eNB to a UE.

For example, only the L parameter sets {ss^(PUSCH) ^(_) ^(UE)(0), Δ_(ss)^(PUSCH) ^(_) ^(UE)(1), . . . , Δ_(ss) ^(PUSCH) ^(_) ^(UE)(L−1)} for thePUSCH may be signaled to the UE, and the M parameters for the PUCCH maynot be signaled. Here, the eNB may signal only the value M to the UE. Assuch, the UE may determine first M parameters {PUSCH UE(0), ss^(PUSCH)^(_) ^(UE)(1), . . . , Δ_(ss) ^(PUSCH) ^(_) ^(UE)(M−1)} among the L RSparameters for the PUSCH as the RS parameter set for the PUCCH. That is,Δ_(ss) ^(PUCCH) ^(_) ^(UE)(0)=Δ_(ss) ^(PUSCH) ^(_) ^(UE)(0), . . . ,Δ_(ss) ^(PUCCH) ^(_) ^(UE)(M−1)=Δ_(ss) ^(PUSCH) ^(_) ^(UE)(M−1) may bedetermined.

For the above-described implicit determination of the RS parameter set,the mapping relationship may be pre-defined. The mapping relationshipmay be semi-statically signaled through RRC signaling, or dynamicallysignaled using specific DCI.

In a system environment in which a larger number of PUCCH target RPscompared to the number of PUSCH target RPs is advantageous, L may berestricted to L≤M oppositely to the above description. In this case, theL RS parameter sets for the PUSCH may be configured as a subset of the MRS parameter sets for the PUCCH, or may be implicitly determined on thebasis of a predetermined mapping relationship based on the M RSparameter sets for the PUCCH.

Further, when M is determined as the number of PUCCH target RPs as inthe current embodiment, an RS parameter set to be applied to a PUCCHformat (e.g., dynamic PUCCH format 1a/1b) for dynamic ACK/NACKtransmission may be dynamically determined among the M RS parametersets. For example, when ACK/NACK is transmitted on a PUCCH in responseto a PDSCH scheduled using a DL-related DCI format of a specific PDCCH,the RS parameter set to be applied to the PUCCH may be dynamicallyindicated using a specific bit or field in the DL-related DCI format. Inother words, since the PUCCH RS parameter set is configured tocorrespond to the number of PUCCH target RPs as described above, RPs towhich ACK/NACK is transmitted on the PUCCH may be determined using thespecific bit or field in the DL-related DCI format. The informationindicating a specific RS parameter set (or specific target RP) may alsobe dynamically indicated for other PUCCH formats not used to transmitACK/NACK.

If the previous proposals of Embodiment 1-A-i and/or Embodiment 1-A-i′are applied together with the current proposal of Embodiment 1-A-ii, thevalue M may be configured in consideration of the number of PUCCH formatgroups in addition to the number of PUCCH target RPs. For example, anumber of Δ_(ss) ^(PUCCH) ^(_) ^(UE) values may be configured tocorrespond to the number of PUCCH format groups, and Δ_(ss) ^(PUCCH)^(_) ^(UE) for dynamically indicating one of a plurality of target RPsmay be additionally configured for a specific PUCCH format, therebydetermining the value M corresponding to the number of all possiblecases. In this case, L≤M may be configured.

Embodiment 1-A-iii

N may refer to the number of SRS target RPs. As such, an SRS can betransmitted per a target RP.

Here, L may be restricted to L≥N. Since L corresponds to the number ofPUSCH target RPs and N corresponds to the number of SRS target RPs asdescribed above, the number of PUSCH target RPs may be restricted to beequal to or greater than the number of SRS target RPs. This restrictionconsiders that Tx power control of an SRS is determined to have apredetermined difference value from Tx power of a PUSCH based on linkadaptation. That is, since the number of PUSCH target RPs is configuredto be equal to or greater than the number of SRS target RPs, flexibilityof PUSCH target RPs may be further ensured.

Further, all of N Δ_(ss) ^(SRS) ^(_) ^(UE) values may be configured as asubset of L Δ_(ss) ^(PUSCH) ^(_) ^(UE) values. This means that an SRSbase sequence is configured to correspond to each of a subset of PUSCHtarget RPs.

Alternatively, all of N Δ_(ss) ^(SRS) ^(_) ^(UE) values may beconfigured to have exactly the same values as all or a part of L Δ_(ss)^(PUSCH) ^(_) ^(UE) values in one to one manner. For example, Δ_(ss)^(PUSCH) ^(_) ^(UE)(0)=Δ_(ss) ^(SRS) ^(_) ^(UE)(0), Δ_(ss) ^(PUSCH) ^(_)^(UE))=Δ_(ss) ^(SRS) ^(_) ^(UE)(1), . . . , Δ_(ss) ^(PUSCH) ^(_)^(UE)(N−1)=Δ_(ss) ^(SRS) ^(_) ^(UE)(N−1) may be configured.

As described above, if parameter sets of different RS types (e.g., PUSCHDMRS and SRS) are repeated partially or entirely, the parameter sets forthe RS types do not need to be separately signaled and thus signaling ofthe RS parameter set for any one RS type may be omitted. In this case,the not-signaled parameter set of the RS type (e.g., SRS) may beimplicitly determined using a mapping relationship based on the signaledparameter set of the RS type (e.g., PUSCH DMRS). The mappingrelationship may be pre-defined or may be separately signaled from aneNB to a UE.

For example, only the L parameter sets {Δ_(ss) ^(PUSCH) ^(_) ^(UE)(0),Δ_(ss) ^(PUSCH) ^(_) ^(UE)(1), . . . , Δ_(ss) ^(PUSCH) ^(_) ^(UE)(L−1)}for the PUSCH may be signaled to the UE, and the N parameters for theSRS may not be signaled. Here, the eNB may signal only the value N tothe UE. As such, the UE may determine first N parameters {Δ_(ss)^(PUSCH) ^(_) ^(UE)(0), Δ_(ss) ^(PUSCH) ^(_) ^(UE)), . . . , Δ_(ss)^(PUSCH) ^(_) ^(UE)(N−1)} among the L RS parameters for the PUSCH as theRS parameter set for the SRS. That is, Δ_(ss) ^(SRS) ^(_)^(UE)(0)=Δ_(ss) ^(PUSCH) ^(_) ^(UE)(0), . . . , Δ_(ss) ^(SRS) ^(_)^(UE)(M−1)=Δ_(ss) ^(PUSCH) ^(_) ^(UE)(N−1) may be determined.

For the above-described implicit determination of the RS parameter set,the mapping relationship may be pre-defined. The mapping relationshipmay be semi-statically signaled through RRC signaling, or dynamicallysignaled using specific DCI.

Embodiment 1-A-iv

N may refer to the number of SRS Power Control (PC) processes.

For example, in a Heterogeneous Network (HetNet) including both amacro-cell and a pico-cell, although a downlink serving cell is themacro-cell, an uplink reception point can be configured as the pico-cellgeographically closer to a CoMP UE (particularly, case of TDD). An SRStransmitted by the CoMP UE to the pico-cell may be used to correctlydetermine uplink CSI by the pico-cell (hereinafter referred to as aUL-CSI acquisition SRS). An SRS transmitted by the CoMP UE to themacro-cell may be used to correctly determine downlink CSI by themacro-cell (hereinafter referred to as a DL-CSI acquisition SRS). Forexample, since uplink and downlink are distinguished from each other bytime on the same frequency in a TDD system, the downlink CSI may bedetermined from an SRS transmitted in uplink due to reciprocity ofuplink and downlink. Here, the UL-CSI acquisition SRS and the DL-CSIacquisition SRS may be configured to follow different PC processes. Inthe above example, the UL-CSI acquisition SRS is directed to thepico-cell which is close to the CoMP UE and thus a PC process mayoperate with relatively low Tx power. On the other hand, the DL-CSIacquisition SRS is directed to the macro-cell which is away from theCoMP UE and thus a PC process may operate with relatively high Tx power.In this case, since the number of different PC processes associated withSRS is 2, N=2 may be configured and a total of 2 RS parameter sets(e.g., 2 Δ_(ss) ^(SRS) ^(_) ^(UE) values) for the UL-CSI acquisition SRSand the DL-CSI acquisition SRS may be configured.

Another example of different SRS PC processes include an SRS PC processtied with a PUSCH PC process for link adaptation of a PUSCH, and aDL-CSI acquisition SRS PC process.

If the previous proposal of Embodiment 1-A-iii is applied together withthe current proposal of Embodiment 1-A-iv, the value N may be configuredin consideration of the number of SRS target RPs in addition to thenumber of SRS PC processes. For example, a number of Δ_(ss) ^(SRS) ^(_)^(UE) values may be configured to correspond to the number of SRS PCprocesses, and Δ_(ss) ^(SRS) ^(_) ^(UE) for dynamically indicating aspecific RP among a plurality of target RPs may be additionallyconfigured for a specific SRS PC process, thereby determining the valueN corresponding to the number of all possible cases. In this case, L≤Nmay be configured.

Embodiment 1-A-v

The current embodiment relates to a method for dynamically signalingwhich RS parameter is applied among RS parameter sets forPUSCH/PUCCH/SRS which are signaled by a higher layer based on the PUCCHRS parameter set grouping method, the SRS RS parameter set groupingmethod, and the method using correlations among PUSCH/PUCCH/SRS RSparameter sets, as proposed above in Embodiments 1-A-i to 1-A-iv.

For example, a parameter may be dynamically selected from the PUSCH RSparameter set {Δ_(ss) ^(PUSCH) ^(_) ^(UE)(0), Δ_(ss) ^(PUSCH) ^(_)^(UE)(1), . . . , Δ_(ss) ^(PUSCH) ^(_) ^(UE)(L)} through dynamicindication at a specific time. Alternatively, a parameter may bedynamically selected from the PUCCH RS parameter set {Δ_(ss) ^(PUCCH)^(_) ^(UE)(0), Δ_(ss) ^(PUCCH) ^(_) ^(UE)(1), . . . , Δ_(ss) ^(PUCCH)^(_) ^(UE)(M)} through dynamic indication at a specific time. Otherwise,a parameter may be dynamically selected from the SRS RS parameter set{Δ_(ss) ^(SRS) ^(_) ^(UE)(0), Δ_(ss) ^(SRS) ^(_) ^(UE)(1), . . . ,Δ_(ss) ^(SRS) ^(_) ^(UE)(N)} through dynamic indication at a specifictime. That is, when L RS parameter set candidates are configured for thePUSCH, M RS parameter set candidates are configured for the PUCCH, or NRS parameter set candidates are configured for the SRS, which RSparameter set among those RS parameter set candidates is actually usedto generate a PUSCH/PUCCH/SRS RS base sequence may be dynamicallyindicated.

For example, one of the L PUSCH RS parameter sets may be indicated usinga specific bit of a DCI format (e.g., DCI format 0 or 4, hereinafterreferred to as a UL-related DCI format) including a PUSCH scheduling ULgrant. For this dynamic indication, a new bit(s) may be newly added tothe corresponding DCI format or an already defined specific bit(s) maybe reused for dynamic indication of the RS parameter set. For example,fields defined in the UL-related DCI format include 1 bit indicatinguplink multi-cluster Resource Allocation Type (RAT), and this may bereused (or implicitly indicated) as the dynamic indicator bit of the RSparameter set. When carrier aggregation by which a plurality of cellsare configured for a UE is supported, resource utilization can beincreased by assigning a non-contiguous frequency band to a UE locatedat the center of a cell, and the RAT indication bit is used to indicatewhether uplink multi-cluster frequency allocation is applied. Ingeneral, it can be assumed that a UE operating according to the presentinvention to generate an RS base sequence for coordinated communicationwith multiple cells is located at a cell edge and communicates with aserving cell and a neighbor cell(s). Accordingly, since multi-clusteruplink frequency allocation is not applied to the UE located at a celledge in most cases, a reduction in system performance may not beexpected even when the RAT indication bit is used for another purpose.

In the case of PUCCH, for a PUCCH format for ACK/NACK transmission, aspecific bit(s) in a DL-related DCI format which carries information forscheduling downlink transmission associated with corresponding ACK/NACKmay be used to indicate one of the M RS parameter sets for the PUCCH.

In the case of SRS, a specific bit(s) in a DCI format (e.g., DCI format0/1A/4 for FDD, DCI format 0/1A/2B/2C/4 for TDD) for triggering anaperiodic SRS (A-SRS) may be used to indicate one of the N RS parametersets for the SRS.

The above method for dynamically indicating an RS parameter set forPUSCH/PUCCH/SRS is purely exemplary, and the scope of the presentinvention includes a method for dynamically indicating an RS parameterset using a predetermined bit which is present in a DCI format.

Embodiment 1-B

As described above in Embodiment 1, in the above method for notsignaling a VCI value separately but using a PCI value of a serving cellas the VCI value, a restriction may be applied to PCIs of cellsbelonging the same CoMP cluster.

Specifically, the present invention proposes to configure PCIs of cellsbelonging the same CoMP cluster to satisfy the same floor(PCI/30) value.Here, floor(x) denotes a maximum integer not greater than x. Forexample, when a network assigns PCI1 to cell1, PCI2 to cell2, and PCI3to cell3 (where PCI1 PCI2 PCI3), values satisfyingfloor(PCI1/30)=floor(PCI2/30)=floor(PCI3/30) as the PCI1, PCI2 and PCI3values. Further, considering that up to 30 different PCIs can have thesame floor(PCI/30) value and a PCI can be reused (or repeated) amongcells spaced geographically sufficiently apart from each other, thepossibility of lack of PCI resources is extremely low even when PCIassignment restriction proposed by the present invention is applied.

When PCIs of cells belonging the same CoMP cluster are assigned to havethe same floor(PCI/30) value as described above, all cells in thecluster have the same initial value c_(init)=└PCI/30┘ (see Equation 10)of a group hopping pattern f_(gh)(n_(s)) pseudo-random sequencegenerator. This means that a PCI (or VCI) of a specific cell does notneed to be signaled to a UE even when PUSCH DMRS/PUCCH DMRS/SRS istransmitted to another cell in the CoMP cluster, because the UE canacquire the same RS base sequence using a PCI of a serving cell thereofcompared to a case in which a PCI of the other cell is used. Here, sinceacquisition of the same RS base sequence in terms of group hoppingpattern means that the group hopping base sequence used by the UE of theserving cell is the same as that used by another UE of another cell aswell as another UE of the serving cell, orthogonality of RSs receivedfrom different UEs may be ensured by varying only a cyclic shift (CS).Accordingly, although a network does not separately signal a VCI to aUE, the UE may use a PCI of a serving cell thereof.

Accordingly, only an RS parameter set (e.g., Δ_(ss)) corresponding to atarget cell (or target RP) may be signaled to a CoMP UE as describedabove in Embodiment 1-A to allow the CoMP UE to transmit PUSCHDMRS/PUCCH DMRS/SRS to a cell other than a serving cell.

In brief, a VCI may be configured in such a manner that a floor(VCI/30)value of the VCI among RS parameter sets for PUSCH/PUCCH/SRS used toapply the methods proposed by specific embodiments of Embodiment 1-A hasthe same value as floor(PCI/30) of a PCI used to support legacy UEs by atarget RP. Here, the VCI may not be explicitly signaled, and a rule touse a specific PCI (e.g., a PCI of a serving cell) may be pre-defined.

The reason why the VCI is restricted as described above is because,since a UL PUSCH DMRS/PUCCH DMRS/SRS is configured by applying 17hopping patterns to 30 sequences (see above description associated withEquation 6), when the value of floor(VCI/30) is different from the valueof floor(PCI/30), collision can occur due to the difference between anRS base sequence generated based on the VCI and an RS base sequencegenerated based on the PCI. Accordingly, in a CoMP operation by which aplurality of RPs share the same PCI, the relationship between VCI andPCI for each RP may be correctly supported. Further, PCIs of cells in aCoMP cluster may be configured to satisfy floor(VCI/30)=floor(PCI/30).

Although a method for allowing a UE to use a PCI of a serving cell as aVCI has been described in the above embodiments, according to otherembodiments of the present invention, a specific PCI (the PCI of theserving cell or another PCI) may be signaled to the UE and then theabove descriptions may be equally applied. For example, a specific PCIvalue (this value does not need to be the PCI of the serving cell) maybe signaled as a VCI through RRC signaling to commonly use the VCI(i.e., specific PCI), and RS parameter sets for PUSCH/PUCCH/SRS (e.g.,one or more Δ_(ss) ^(PUSCH) ^(_) ^(UE), one or more Δ_(ss) ^(PUCCH) ^(_)^(UE), one or more Δ_(ss) ^(SRS) ^(_) ^(UE)) may be signaled throughUE-specific RRC signaling. Further, use of a specific parameter setamong the RS parameter sets signaled through RRC signaling may beindicated through dynamic signaling.

A floor(PCI/30) value of the specific PCI signaled as the VCI may bedifferent from a floor(PCI/30) value of the PCI of the serving cell. Ifthis specific PCI is signaled through RRC signaling, the UE may applythe specific PCI to an equation associated with an initial valuec_(init) of a pseudo-random sequence generator of a group hoppingpattern f_(gh)(n_(s)). In addition, the UE may generate an RS basesequence based on dynamic signaling of another RS parameter (e.g.,Δ_(ss)).

When no specific PCI is signaled as the VCI through RRC signaling, arule to basically generate an RS base sequence using the PCI of theserving cell may be pre-defined.

Alternatively, information indicating one of a plurality of PCIsincluding the PCI of the serving cell, as a VCI parameter to be appliedto generate an RS base sequence may be defined in the form of a specificbit(s), and this may be provided to the UE through RRC signaling ordynamic signaling.

Embodiment 1-C

The current embodiment relates to specific embodiments of Embodiments1-A and 1-B for applying a specific PCI value (e.g., a PCI of a servingcell or a specific PCI determined using the above restriction) as a VCIand generating an RS base sequence of PUSCH DMRS/PUCCH DMRS/SRS usingUE-specifically signaled Δ_(ss) parameters.

In the case of PUSCH DMRS, to determine a base sequence index u (i.e.,group hopping index) defined as shown in Equation 6, an initial valuec_(init) of a pseudo-random sequence generator of a group hoppingpattern f_(gh)(n_(s)) may be determined based on c_(init)=└PCI/30┘(where PCI may refer to the specific PCI signaled as the VCI) as shownin Equation 10. In addition, a sequence shift pattern f_(ss) may bedetermined as shown in Equation 19.f _(SS) ^(PUSCH)={(PCI mod 30)+Δ_(ss) ^(PUSCH) ^(_) ^(UE)(l)} mod30  [Equation 19]

In Equation 19, PCI may refer to the specific PCI signaled as the VCI.In Equation 19, l=0, . . . , L.

In the case of PUCCH DMRS, the initial value of the pseudo-randomsequence generator of the group hopping pattern may be determined basedon c_(init)=└PCI/30┘ (where PCI may refer to the specific PCI signaledas the VCI). The sequence shift pattern f_(ss) may be determined asshown in Equation 20.f _(SS) ^(PUCCH)={(PCI mod 30)+Δ_(ss) ^(PUCCH) ^(_) ^(UE)(m)} mod30  [Equation 20]

In Equation 20, PCI may refer to the specific PCI signaled as the VCI.In Equation 20, m=0, . . . , M.

Alternatively, when the legacy calculation method of Equation 11 isused, f_(SS) ^(PUCCH)=PCI mod 30 (where PCI may refer to the specificPCI signaled as the VCI) may be defined. In this case, an RS parameterset {Δ_(ss) ^(PUCCH) ^(_) ^(UE)(0), Δ_(ss) ^(PUCCH) ^(_) ^(UE), . . . ,Δ_(ss) ^(PUCCH) ^(_) ^(UE)(M)} for the PUCCH DMRS may operate to beexcluded from UE-specific RRC signaling (i.e., not to be signaled).

In the case of SRS, the initial value of the pseudo-random sequencegenerator of the group hopping pattern may be determined based onc_(init)=└PCI/30┘ (where PCI may refer to the specific PCI signaled asthe VCI). The sequence shift pattern f_(ss) may be determined as shownin Equation 21.f _(SS) ^(SRS)={(PCI mod 30)+Δ_(ss) ^(SRS) ^(_) ^(UE)(n)} mod30  [Equation 21]

In Equation 21, PCI may refer to the specific PCI signaled as the VCI.In Equation 21, n=0, . . . , N.

As described above in the paragraph above Equation 18, a base sequenceindex u (i.e., group hopping index) used to generate a legacy SRS basesequence is defined to follow a sequence group number of a PUCCH DMRS.However, in the present invention, a parameter independent from aparameter applied to the PUCCH DMRS may be used for an SRS to calculatea sequence shift pattern, and thus the base sequence of the SRS may begenerated independently from the base sequence of the PUCCH DMRS.

Embodiment 2

In a legacy method for determining a sequence shift pattern f_(ss) of anRS base sequence (see Equation 12, for example), a PCI (i.e., N_(ID)^(cell)) and an offset value (i.e., Δ_(ss)) are used. Here, the PCIranges from 0 to 503. Since the values 0 to 503 of the PCI are notsufficient to cover 510 possible cases (i.e., 30 base sequence groups×17sequence group hopping patterns), the offset value (i.e., Δ_(ss)) isdefined and used.

In a method for determining a base sequence index for PUSCH DMRS/PUCCHDMRS/SRS according to the present invention, a sequence shift patternf_(ss) may be determined using a VCI indicated through higher layersignaling without using Δ_(ss) (or configuring Δ_(ss)=0). Since Δ_(ss)is used in the sequence shift pattern determination method defined for alegacy wireless communication system to cover 30 base sequence groupsand 17 sequence group hopping patterns as described above, the range ofthe VCI needs to be newly defined when only the VCI is used withoutusing Δ_(ss), and the present invention proposes to define the VCI torange from 0 to 509. VCI information configured to one of the values 0to 509 may be RRC signaled to a UE.

When various proposals of the present invention described above inEmbodiment 1 are used together with the VCI ranging from 0 to 509, an RSparameter set may be additionally signaled to the UE. For example, an RSparameter set (e.g., Δ_(ss) ^(PUCCH) ^(_) ^(UE)(s) and/or Δ_(ss) ^(SRS)^(_) ^(UE)(s)) for transmitting a PUCCH DMRS and/or an SRS to another RPmay be provided. Further, an RS parameter set (e.g., Δ_(ss) ^(PUSCH)^(_) ^(UE)(s)) for transmitting a PUSCH to another RP may be provided.That is, one or more of the VCI (e.g., ranging from 0 to 509), the RSparameter set for the PUSCH, the RS parameter set for the PUCCH and theRS parameter set for the SRS may be provided through UE-specific RRCsignaling.

In addition, the part associated with a specific PCI used withoutsignaling a VCI in Embodiment 1 may be replaced with a VCI (i.e., VCIranging from 0 to 509) signaled in Embodiment 2, and the otheroperations may be equal.

Embodiment 3

A method for defining and using an RS parameter set (VCI and/or Δ_(ss))to generate a base sequence of a PUCCH DMRS and/or an SRS has beendescribed above in Embodiments 1 and 2. The current embodiment proposeselements to be additionally included in an RS parameter set. One or moreof various parameters described below may be provided throughUE-specific RRC signaling. For example, the various parameters describedbelow may be signaled together with VCI and/or Δ_(ss). Alternatively, aparameter(s) to be cell-specifically and/or UE-specifically providedaccording to operation defined in a legacy wireless communication systemamong the various parameters described below may be signaled separatelyfrom VCI and/or Δ_(ss) or may not be signaled to reuse a previouslyprovided parameter.

Embodiment 3-A

In the case of PUCCH, a parameter for generating a DMRS sequencedirected to a specific cell (e.g., a cell other than a serving cell) mayinclude all cell-specific parameters of the specific cell.

For example, Δ_(shift) ^(PUCCH), δ_(offset) ^(PUCCH), β_(PUCCH) andN_(PUCCH) ⁽¹⁾ to be provided to a UE(s) served by a second cell may beprovided to a UE served by a first cell.

Δ_(shift) ^(PUCCH) is a cell-specific parameter for determining a CSinterval to determine a PUCCH OCC and a CS index, and may be configuredto one of 1, 2 and 3 for a normal CP and to one of 2 and 3 for anextended CP.

δ_(offset) ^(PUCCH) is a parameter configured for inter-cellinterference randomization, and may be configured to one of {0, 1, . . ., Δ_(shift) ^(PUCCH)−1}.

β_(PUCCH) is an amplitude scaling factor used to determine PUCCH Txpower.

N_(PUCCH) ⁽¹⁾ is a parameter UE-specifically configured to determine aPUCCH resource offset. N_(PUCCH) ⁽¹⁾ is used to determine n_(PUCCH) ⁽¹⁾indicating a PUCCH resource index (i.e., PUCCH CS index), and refers toa start point (i.e., offset) of a PUCCH resource region.

In addition, a new parameter representing a resource region in which aPUCCH is transmitted may be defined and used. For example, a PRB numbercorresponding to a PUCCH transmission resource may be explicitlyprovided through UE-specific signaling.

In this case, as a DMRS sequence (i.e., a base sequence determined basedon a VCI value) is changed, the UE-specific N_(PUCCH) ⁽¹⁾ or the PUCCHresource PRB index value may be correspondingly changed. Further,additional signaling for indicating this may be defined and used.

The above-described UE-specific PUCCH resource indication parameters arecollectedly denoted by N_(PUCCH) _(_) _(UE) ⁽¹⁾ in the presentinvention. N_(PUCCH) _(_) _(UE) ⁽¹⁾ may be configured to a valueindependent from N_(PUCCH) ⁽¹⁾ cell-specifically configured in acorresponding cell.

Further, an N_(PUCCH) _(_) _(UE) ⁽¹⁾ value to be commonly applied todynamic PUCCH format 1a/1b and/or dynamic PUCCH format 3 triggered by alegacy PDCCH, and dynamic PUCCH format 1a/1b and/or dynamic PUCCH format3 triggered by an ePDCCH may be configured.

Alternatively, an N_(PUCCH) _(_) _(UE) ⁽¹⁾ value to be applied todynamic PUCCH format 1a/1b and/or dynamic PUCCH format 3 triggered by alegacy PDCCH, and N_(PUCCH) _(_) _(UE) ^((1)′) which is independent fromN_(PUCCH) _(_) _(UE) ⁽¹⁾ may be UE-specifically defined and used. Forexample, N_(PUCCH) _(_) _(UE) ^((1)′) may correspond to a PUCCH resourceindication parameter to be applied to dynamic PUCCH format 1a/1b and/ordynamic PUCCH format 3 triggered by an ePDCCH.

Otherwise, an N_(PUCCH) _(_) _(UE) ⁽¹⁾ value to be applied to dynamicPUCCH format 1a/1b and/or dynamic PUCCH format 3 triggered by a legacyPDCCH or ePDCCH received in a CSS may be configured. Here, N_(PUCCH)_(_) _(UE) ⁽¹⁾=N_(PUCCH) ⁽¹⁾ may be configured. In addition to this, anN_(PUCCH) _(_) _(UE) ^((1)′) value to be applied to dynamic PUCCH format1a/1b and/or dynamic PUCCH format 3 triggered by a legacy PDCCH orePDCCH received in a USS may be UE-specifically defined and used.

The additional parameter sets (e.g., Δ_(shift) ^(PUCCH), Δ_(offset)^(PUCCH) and/or β_(PUCCH)) may be additionally configured for each ofN_(PUCCH) _(_) _(UE) ⁽¹⁾ and N_(PUCCH) _(_) _(UE) ^((1)′).

Further, parameters of a serving cell may be applied to PUCCH format1a/1b for dynamic ACK/NACK such that PUCCH format 1a/1b is alwaysdirected to the serving cell, and the above RS parameter sets (e.g.,VCI, Δ_(ss), Δ_(shift) ^(PUCCH), δ_(offset) ^(PUCCH), β_(PUCCH) and/orN_(PUCCH) _(_) _(UE) ⁽¹⁾) may be provided to another PUCCH format (e.g.,PUCCH format 2/2a/2b/3) through UE-specific signaling such that theother PUCCH format is directed to another cell.

In Embodiments 1 and 2, an RS parameter set for generating a basesequence for a PUCCH may include VCI, Δ_(ss), Δ_(shift) ^(PUCCH),δ_(offset) ^(PUCCH), β_(PUCCH) and/or N_(PUCCH) _(_) _(UE) ⁽¹⁾.

Embodiment 3-B

In the case of SRS, a parameter for generating an SRS sequence directedto a specific cell (e.g., a cell other than a serving cell) may includeall cell-specific parameters of the specific cell.

For example, n_(SRS) ^(cs), β_(SRS), N_(ap), k₀ ^((p)), M_(sc,b) ^(RS),C_(SRS), B_(SRS), srsMaxUpPts, k _(TC), n_(b), n_(hf), b_(hop), T_(SRS),T_(offset), T_(SFC) and Δ_(SFC) to be provided to a UE(s) served by asecond cell may be provided to a UE served by a first cell.

n_(SRS) ^(cs) may be configured to one of {0, 1, 2, 3, 4, 5, 6, 7}, andis provided for each UE. n_(SRS) ^(cs) may be configured by higher layerparameters cyclicshift and cyclicshift-ap individually for a periodicSRS configuration and an aperiodic SRS configuration.

β_(SRS) is an amplitude scaling factor used to determine SRS Tx powerP_(SRS).

N_(ap) indicates the number of antenna ports used for SRS transmission.A set of antenna ports used for SRS transmission may be configuredindividually for a periodic SRS configuration and an aperiodic SRSconfiguration.

k₀ ^((p)) is a parameter for determining the starting position of theSRS in the frequency domain when a UE-specific parameter for determiningan SRS bandwidth (i.e., b) is given as B_(SRS).

M_(sc,b) ^(RS) indicates the length of a sounding reference signal andis given as M_(sc,b) ^(RS)=m_(SRS,b)N_(sc) ^(RB)/2.

C_(SRS) is a cell-specific parameter srs-BandwidthConfig indicating aset of configurations of the SRS bandwidth, and is configured to one of{0, 1, 2, 3, 4, 5, 6, 7} by a higher layer.

B_(SRS) is a UE-specific parameter srs-Bandwidth associated with the SRSbandwidth, and is configured to one of {0, 1, 2, 3} by a higher layer.

For a UpPTS, if reconfiguration of m_(srs,0) is enabled by acell-specific parameter srsMaxUpPts given by a higher layer, m_(SRS,0)^(max)=max_(cϵC){m_(SRS,0) ^(c)}≤(N_(RB) ^(UL)−6N_(RA)) may bereconfigured. If reconfiguration is disabled, m_(SRS,0) ^(max)=m_(SRS,0)is given. Here, c denotes an SRS bandwidth configuration, and N_(RA)denotes the number (i.e., index) of a format 4 Physical Random AccessChannel (PRACH) in a corresponding UpPTS.

k _(TC)ϵ{0, 1} is signaled by a higher layer using a UE-specificparameter transmissionComb or transmissionComb-ap defined individuallyfor a periodic SRS configuration and an aperiodic SRS configuration.

n_(b) indicates a frequency position index.

n_(hf) is given as 0 in a UpPTS of a first half frame of a radio frame,and as 1 in a UpPTS of a second half frame.

b_(hop)ϵ{0, 1, 2, 3} is a parameter for configuring frequency hopping ofthe SRS, and is provided using a higher layer parametersrs-HoppingBandwidth. Frequency hopping is not supported for aperiodicSRS transmission. When frequency hopping of the SRS is not enabled(i.e., if b_(hop)≥B_(SRS)), the frequency position index n_(b) ismaintained as a constant as long as reconfiguration is not performed,and n_(b)=└4n_(RRC)/m_(SRS,b)┘ mod N_(b) is defined. Here, a parametern_(RR)C is given by higher layer parameters freqDomainPosition andfreqDomainPosition-ap individually for a periodic SRS configuration andan aperiodic SRS configuration.

T_(SRS) indicates a UE-specific SRS transmission cycle, and T_(offset)is an SRS subframe offset. T_(offset) _(_) _(max) is a maximum value ofT_(offset) at a certain SRS subframe offset.

T_(SFC) indicates a cell-specific subframe configuration cycle for SRStransmission, and Δ_(SFC) is a cell-specific subframe offset for SRStransmission.

In Embodiments 1 and 2, VCI, Δ_(ss), n_(SRS) ^(cs), β_(SRS), N_(ap), k₀^((p)), M_(sc,b) ^(RS), C_(SRS), B_(SRS), srsMaxUpPts, k _(TC), n_(b),n_(hf), b_(hop), T_(SRS), T_(offset), T_(SFC) and/or Δ_(SFC) may beprovided through UE-specific signaling as an RS parameter set forgenerating a base sequence for an SRS.

Embodiment 3-C

In the case of PUSCH, a parameter for generating a PUSCH DMRS sequencedirected to a specific cell (e.g., a cell other than a serving cell) mayinclude all cell-specific parameters of the specific cell.

For example, n_(DMRS) ⁽¹⁾ and β_(PUSCH) to be provided to a UE(s) servedby a second cell may be provided to a UE served by a first cell.

n_(DMRS) ⁽¹⁾ may have values determined based on a higher layerparameter cyclic shift as shown in Table 4.

TABLE 4 cyclic shift n_(DMRS) ⁽¹⁾ 0 0 1 2 2 3 3 4 4 6 5 8 6 9 7 10

β_(PUCCH) is an amplitude scaling factor used to determine PUSCH Txpower.

In Embodiments 1 and 2, an RS parameter set for generating a basesequence for a PUSCH may include VCI, Δ_(ss), n_(DMRS) ⁽¹⁾ and/orβ_(PUSCH).

Embodiment 4

In the method for generating a base sequence of PUSCH DMRS/PUCCHDMRS/SRS described above in Embodiments 1 to 3, RS parameter setcandidates may be provided through higher layer signaling (e.g., RRCsignaling) and a specific RS parameter set to be used to generate an RSsequence may be indicated among them through dynamic signaling. Suchdynamic signaling may be reinterpreted as adding or substituting dynamicsignaling to or for the original purpose of a specific bit(s) of DCI.Alternatively, for dynamic signaling, a new bit(s) may be additionallydefined in DCI.

Embodiment 5

In Embodiments 1 to 4, when an RS parameter set of PUSCH/PUCCH/SRSincludes or defines Δ_(ss) (e.g., Δ_(ss) ^(PUSCH) ^(_) ^(UE)(s), Δ_(ss)^(PUCCH) ^(_) ^(UE)(s) and/or Δ_(ss) ^(SRS) ^(_) ^(UE)(s)) for acorresponding channel/signal, the Δ_(ss) value may be configured to oneof 0 to 29.

Embodiment 6

The current embodiment relates to a method for UE-specificallyconfiguring a VCI for determining a base sequence of PUSCH/PUCCH/SRSand/or a CS hopping pattern, independently for each of the PUSCH, thePUCCH and the SRS or for a partial group thereof.

For example, parameter sets of {VCI_PUSCH, VCI_PUCCH, VCI_SRS} may beprovided to a specific UE through RRC signaling.

If the PUSCH is supported to be selectively directed to a plurality ofRPs (e.g., if dynamic switching among a plurality of DMRS configurationsis supported), VCI_PUSCH among the UE-specific parameter sets may beconfigured and signaled in the form of {VCI_PUSCH₁, . . . ,VCI_PUSCH_(L)}.

If the PUCCH is supported to be selectively directed to a plurality ofRPs or if the VCI is allowed to apply a different value per a PUCCHformat (group), VCI_PUCCH among the UE-specific parameter sets may beconfigured and signaled in the form of {VCI_PUCCH₁, . . . ,VCI_PUCCH_(M)}.

If the SRS is supported to be selectively directed to a plurality ofRPs, VCI_SRS among the UE-specific parameter sets may be configured andsignaled in the form of {VCI_SRS₁, . . . , VCI_SRS_(N)}.

Here, the range of the VCI_PUSCH, VCI_PUCCH and/or VCI_SRS value may begiven as 0 to 509 as described above in Embodiment 2.

Embodiment 6-A

When dynamic switching among a plurality of PUSCH DMRS configurations issupported, if, for example, 2 VCIs are necessary for a PUSCH, RSparameter sets may be configured and signaled in the form of{VCI_PUSCH₁, VCI_PUSCH₂, VCI_PUCCH, VCI_SRS}.

If an RS parameter set is defined to include a plurality of VCIs andΔ_(ss) values and Δ_(ss) is additionally configured for each VCI, the RSparameter set may be configured and signaled in the form of {VCI_PUSCH₁,Δ_(ss1), VCI_PUSCH₂, Δ_(ss2)}. In this case, since a sequence shiftpattern is determined based on VCI and Δ_(ss), the range of VCI_PUSCHmay be configured to 0 to 503.

If a PUCCH is configured to be directed to a single RP only, VCI_PUCCHmay be configured to use specific VCI_PUSCH_(n). For example, if a firstVCI configured for the PUSCH is configured to be used for the PUCCH,VCI_PUCCH=VCI_PUSCH₁ may be configured or pre-defined.

If an RS parameter set is defined to include a plurality of VCIs andΔ_(ss) values and common Δ_(ss) is configured for the VCIs, the RSparameter set may be configured and signaled in the form of {VCI_PUSCH₁,Δ_(ss1), VCI_PUSCH₂}. For example, if a first VCI configured for thePUSCH is configured to be used for the PUCCH, VCI_PUCCH=VCI_PUSCH₁ maybe configured or pre-defined.

If an RS parameter set is defined to include a plurality of VCIs andΔ_(ss) values and Δ_(ss) is applied to some VCIs and not to the otherVCIs, the RS parameter set may be configured and signaled in the form of{VCI_PUSCH₁, Δ_(ss1), VCI_PUSCH₂}. For example, if a first VCIconfigured for the PUSCH is configured to be used for the PUCCH,VCI_PUCCH=VCI_PUSCH₁ may be configured or pre-defined. Here, Δ_(ss1) maybe pre-defined to be applied to VCI_PUSCH₁ only.

Embodiment 6-B

If a VCI is applied to a PUSCH but not is not changed for a PUCCH (or ifa legacy PCI is applied to the PUCCH), an RS parameter set may beconfigured and signaled in the form of {VCI_PUSCH₁}. Here, as describedabove in Embodiment 2, the range of VCI_PUSCH₁ may be configured to 0 to509. As such, since VCI_PUCCH=PCI, a legacy operation for generating aPUCCH DMRS sequence is not changed.

However, if the VCI is applied to the PUCCH but is not changed for thePUSCH (or if a legacy PCI is applied to the PUSCH), an RS parameter setmay be configured and signaled in the form of {VCI_PUCCH}.

When the RS parameter set for the PUSCH is configured to include VCI andΔ_(ss) (i.e., {VCI_PUSCH₁, Δ_(ss1)}) and then signaled, a specificbit(s) indicating whether the signaled VCI is applied to the PUCCH maybe defined and signaled. That is, when only the VCI for the PUSCH (e.g.,VCI_PUSCH₁) is signaled, information indicating whetherVCI_PUCCH=VCI_PUSCH₁ is configured may be defined and signaled. When theinformation is defined to have a 1-bit size, for example, if the bitvalue is 0, this may indicate that the signaled VCI is applied to thePUSCH only. If the bit value is 1, this may indicate that the signaledVCI is applied to both the PUSCH and the PUCCH.

Although the RS parameter set for the PUSCH includes 2 VCIs in the aboveembodiments, the scope of the present invention is not limited thereto.That is, the RS parameter set may be extended to 3 or more RS parametersand the RS parameters may also be applied to the PUCCH and/or the SRSaccording to the above-described methods (e.g., case of one or more VCIsonly, case of one or more VCIs and Δ_(ss) values, case ofindividual/common Δ_(ss), etc.) when one or more RS parameter sets areconfigured and signaled for the PUCCH and/or the SRS. Further, whether aparameter set for any one type RS among PUSCH DMRS/PUCCH DMRS/SRS isequally applied to the other type RSs may be configured.

Embodiment 7

A method for configuring and signaling an RS parameter set for a UL RS(e.g., PUSCH DMRS/PUCCH DMRS/SRS) has been mainly described above inEmbodiments 1 to 6. Embodiment 7 describes a method for configuring andsignaling an RS parameter set of a DL RS (e.g., CSI-RS and/orUE-specific RS). Although the following description is focused on theCSI-RS, the same principle may be equally applied to the UE-specific RS.

As described above in relation to Equations 2 and 4, according tooperation of the legacy wireless communication system, an initial valuec_(init) for generating a DL RS sequence is determined based on a PCI(i.e., N_(ID) ^(cell) of a serving cell). The present invention proposesa method for correctly detecting and receiving a DL RS transmitted froma cell other than a serving cell, by a CoMP UE using a VCI instead of aPCI to correctly support CoMP operation. Information about an RSparameter set including the VCI for generating a DL RS may be providedto the UE through higher layer signaling. For example, in the case ofCSI-RS, the RS parameter set including the VCI may be signaled to the UEthrough RRC signaling about CSI-RS configuration.

Although an RS parameter set including a VCI and the like for a DL RScan be explicitly signaled to a UE as described above, the RS parameterset applied to the DL RS may be indirectly determined based on an RSparameter set for a UL RS (e.g., PUSCH/PUCCH/SRS). That is, an RSparameter set may be configured independently for each of a PUSCH DMRS,a PUCCH DMRS, an SRS, a CSI-RS and a UE-specific RS.

Alternatively, by configuring a dependent relationship (or mappingrelationship) among the PUSCH DMRS, the PUCCH DMRS, the SRS, the CSI-RSand the UE-specific RS, a parameter for one type RS may be applied as aparameter for one or more other type RSs (i.e., common RS parameter). Assuch, a RS parameter set per an RS type or per an RS type group may beconfigured through, for example, UE-specific RRC signaling, and amapping relationship among RS parameter sets for different type RSs (orRS groups) may be configured.

For clarity of explanation, the following description is focused on acase in which an RS parameter set directly configured throughUE-specific RRC signaling or indirectly configured (i.e., determinedbased on a mapping relationship with an RS parameter set for anothertype RS) includes one or more VCIs. However, the scope of the presentinvention is not limited thereto and the principle of the presentinvention described below may be equally applied to a case in which Δssor various parameters proposed in Embodiment 3 are include in the RSparameter set.

For example, RS parameters for each RS type may be defined as describedbelow. {VCI_PUSCH₁, . . . , VCI_PUSCH_(L)} may be configured for a PUSCHDMRS, {VCI_PUCCH₁, . . . , VCI_PUCCH_(M)} may be configured for a PUCCHDMRS, {VCI_SRS₁, . . . , VCI_SRS_(N)} may be configured for an SRS,{VCI_X₁, . . . , VCI_X_(P)} may be configured for a CSI-RS, and {VCI_Y₁,. . . , VCI_Y_(Q)} may be configured for a UE-specific RS. Here, L≥1,M≥1, N≥1, P≥1 and Q≥1.

As described above, basically, VCIs for each RS type may be configuredindependently from those of another RS type without dependencytherebetween.

Embodiment 7-a

A one to one mapping relationship may be partially or entirelyconfigured between a VCI(s) for a PUSCH and a VCI(s) for a PUCCH. Assuch, only the VCI for any one of the PUSCH and the PUCCH may beprovided through higher layer signaling, and the VCI for the other onemay be determined based on the one to one mapping relationship. That is,the VCI for the PUSCH and the VCI for the PUCCH may be configured tohave the same value. For example, a relationship ofVCI_PUSCH₁=VCI_PUCCH₁, VCI_PUSCH₂=VCI_PUCCH₂, . . . may be established.

Embodiment 7-b

A one to one mapping relationship may be partially or entirelyconfigured between a VCI(s) for an SRS and a VCI(s) for a PUCCH. Assuch, only the VCI for any one of the SRS and the PUCCH may be providedthrough higher layer signaling, and the VCI for the other one may bedetermined based on the one to one mapping relationship. That is, theVCI for the SRS and the VCI for the PUCCH may be configured to have thesame value. For example, a relationship of VCI_SRS₁=VCI_PUCCH₁,VCI_SRS₂=VCI_PUCCH₂, . . . may be established. This scheme easilysupports an operation for applying a base sequence of a PUCCH equally toa base sequence of an SRS (see the paragraph above Equation 18) andcorresponds to extension of a parameter set (e.g., VCI) for generating abase sequence into a plurality of parameter sets.

Embodiment 7-c

A one to one mapping relationship may be partially or entirelyconfigured between a VCI(s) for an SRS and a VCI(s) for a PUSCH. Assuch, only the VCI for any one of the SRS and the PUSCH may be providedthrough higher layer signaling, and the VCI for the other one may bedetermined based on the one to one mapping relationship. That is, theVCI for the SRS and the VCI for the PUSCH may be configured to have thesame value. For example, a relationship of VCI_SRS₁=VCI_PUSCH₁,VCI_SRS₂=VCI_PUSCH₂, . . . may be established. This scheme easilysupports a Power Control (PC) operation of an SRS which is tied with aPUSCH PC operation for link adaptation of the PUSCH by a difference of apredetermined constant value (e.g., P_(SRS) _(_) _(offset)) and ischaracterized in that, when a plurality of PUSCH VCIs are given, aplurality of SRS VCIs transmittable to corresponding target RPs aregiven due to the tied PC therebetween.

Embodiment 7-d

A one to one mapping relationship may be partially or entirelyconfigured among a VCI(s) for an SRS, a VCI(s) for a PUSCH and a VCI(s)for a PUCCH. As such, only the VCI for any one of the SRS, the PUSCH andthe PUCCH may be provided through higher layer signaling, and the VCIsfor the other two may be determined based on the one to one mappingrelationship. That is, the VCI for the SRS, the VCI for the PUSCH andthe VCI for the PUCCH may be configured to have the same value. Forexample, a relationship of VCI_SRS₁=VCI_PUSCH₁=VCI_PUCCH₁,VCI_SRS₂=VCI_PUSCH₂=VCI_PUCCH₂, . . . may be established. This schemeeasily supports a legacy operation by which the same base sequence isused for the SRS and the PUCCH and also supports tied PC between thePUSCH and the SRS.

Embodiment 7-e

In Embodiments 7-a to 7-d, a one to one mapping relationship of a VCI(s)for a CSI-RS may be additionally defined. For example, a relationship ofVCI_PUSCH₁=VCI_PUCCH₁=VCI_X₁, VCI_PUSCH₂=VCI_PUCCH₂=VCI_X₂, . . . may beestablished in Embodiment 7-a, a relationship ofVCI_SRS₁=VCI_PUCCH₁=VCI_X₁, VCI_SRS₂=VCI_PUCCH₂=VCI_X₂, . . . may beestablished in Embodiment 7-b, a relationship ofVCI_SRS₁=VCI_PUSCH₁=VCI_X₁, VCI_SRS₂=VCI_PUSCH₂=VCI_X₂ . . . may beestablished in Embodiment 7-c, and a relationship ofVCI_SRS₁=VCI_PUSCH₁=VCI_PUCCH₁=VCI_X₂,VCI_SRS₂=VCI_PUSCH₂=VCI_PUCCH₂=VCI_X₂, . . . may be established inEmbodiment 7-d. In addition, a relationship of VCI_SRS₁=VCI_X₁,VCI_SRS₂=VCI_X₂, . . . may be established in Embodiments 7-a to 7-d.

This scheme may correspond to a case in which CSI-RS based Open-LoopPower Control (OLPC) is applied to a cell to which the SRS, the PUSCHand/or the PUCCH are commonly directed, using a CSI-RS configuration forapplying a VCI corresponding to the cell. That is, OLPC for the SRS, thePUSCH and/or the PUCCH is a scheme for determining uplink Tx power by aUE based on indirect information without any direct feedback from aneNB. A reference factor for UL OLPC is a pathloss value, and this can beregarded that the factor is determined based on a value calculated usingthe CSI-RS which is a DL RS from the cell corresponding to the VCI. Thatis, this can be regarded that UL PC and DL PC are tied or that a UL RPand a DL TP correspond to the same point. The above description ispurely exemplary and the mapping relationship among the VCIs for theSRS, the PUSCH, the PUCCH and the CSI-RS may be defined for anotherpurpose.

Embodiment 7-f

In Embodiments 7-a to 7-e, in addition to the RS parameter set for thePUSCH (e.g., VCI_PUSCH, Δ_(ss), n_(DMRS) ⁽¹⁾, β_(PUSCH), etc. inEmbodiment 3-C), a CS hopping initialization parameter (i.e., c_(init)^(CSH)) paired with each PUSCH VCI(s) may be provided throughUE-specific RRC signaling. For example, an RS parameter set may beconfigured and signaled in the form of {(VCI_PUSCH₁, c_(init) ^(CSH) ₁),(VCI_PUSCH₂, c_(init) ^(CSH) ₂), . . . , (VCI_PUSCH_(L), c_(init) ^(CSH)_(L))}. In this case, c_(init) ^(CSH) may be configured independentlyfrom the paired VCI_PUSCH. That is, a base sequence index and a CShopping pattern may independently operate.

Further, each of c_(init) ^(CSH) ₁, c_(init) ^(CSH) ₂, . . . may beallowed to be concurrent with an independent pseudo-random sequencen_(PN)(n_(s)) in parallel. That is, f_(PN,1)(n_(s)) generated based onc_(init) ^(CSH) ₁ may be present and, at the same time, n_(PN,2)(n_(s))generated based on c_(init) ^(CSH) ₂ may be present. Likewise, two ormore c_(init) ^(CSH) values may be concurrent with two or moren_(PN)(n_(s)) values in parallel.

Alternatively, a single pseudo-random sequence n_(PN)(n_(s)) may bepresent for different c_(init) ^(CSH) ₁, c_(init) ^(CSH) ₂, . . . .

Such a pseudo-random sequence generator is initialized to acorresponding c_(init) ^(CSH) at the beginning of each radio frame.

If a specific value (including one or more c_(init) ^(CSH) values) amongc_(init) ^(CSH) ₁, c_(init) ^(CSH) ₂, . . . values is signaled in themiddle of the radio frame (e.g., when a slot index is not 0), instead ofn_(PN)(n_(s)) calculated before the signaled value is received,n_(PN)(n_(s)) calculated again at a current time n_(s) on the assumptionthat the specific value is applied when the radio frame starts may beapplied.

Alternatively, even when the specific value of c_(init) ^(CSH) issignaled in the middle of the radio frame, the previously providedc_(init) ^(CSH) value may be continuously used without applying thenewly received specific value, and then n_(PN)(n_(s)) may be calculatedby applying the received specific value when a next radio frame starts.

In Embodiments 7-a to 7-e, Δ_(ss), Δ_(shift) ^(PUCCH), δ_(offset)^(PUCCH), β_(PUCCH) and/or N_(PUCCH) _(_) _(UE) ⁽¹⁾ paired with thePUCCH VCI(s) in Embodiment 3-A may be provided through UE-specific RRCsignaling as the RS parameter set for the PUCCH. For example, the RSparameter set may be configured and signaled in the form of{(VCI_PUCCH₁, Δ_(shift) ^(PUCCH) ₁, Δ_(offset) ^(PUCCH) ₁, β_(PUCCH 1),N_(PUCCH) ⁽¹⁾ ₁), . . . , (VCI_PUCCH_(M), Δ_(shift) ^(PUCCH) _(M),δ_(offset) ^(PUCCH) _(M), β_(PUCCH M), N_(PUCCH) ⁽¹⁾ _(M))}.

In Embodiments 7-a to 7-e, Δ_(ss), n_(SRS) ^(cs), β_(SRS), N_(ap), k₀^((p)), C_(SRS), B_(SRS), srsMaxUpPts, k _(TC), n_(b), n_(hf), b_(hop),T_(SRS), T_(offset), T_(SFC) and/or Δ_(SFC) paired with the SRS VCI(s)in Embodiment 3-B may be provided through UE-specific RRC signaling asthe RS parameter set for the SRS. For example, the RS parameter set maybe configured and signaled in the form of {(VCI_SRS₁, Δ_(ss1), n_(SRS)^(cs) ₁, β_(SRS 1), N_(ap 1), k₀ ^((p)) ₁, M_(sc,b) ^(RS), C_(SRS),B_(SRS), srsMaxUpPts₁, k _(TC 1), n_(b1), n_(hf 1), b_(hop1), T_(SRS1),T_(offset1), T_(SFC1), Δ_(SFC1)), . . . , (VCI_SRS_(N), Δ_(ssN), n_(SRS)^(cs) _(N), β_(SRS N), N_(ap N), k₀ ^((p)) _(N), M_(sc,b) ^(RS) _(N),C_(SRSN), B_(SRSN), srsMaxUpPts_(N), k _(TCN), n_(bN), h_(f N),b_(hopN), T_(SRSN), T_(offsetN), T_(SFCN), Δ_(SFCN))}.

Embodiment 7-g

An SRS includes a UL-CSI acquisition SRS and a DL-CSI acquisition SRS.The DL-CSI SRS may follow a PC process not tied with PUSCH PC. A VCI(s)applied to this DL-CSI SRS may be {VCI_SRS^(DL) ₁, . . . , VCI_SRS^(DL)_(Q)}(where Q≥1).

In this case, a one to one mapping relationship may be partially orentirely configured between a VCI_SRS^(DL)(s) for the DL-CSI SRS and aVCI X(s) for a CSI-RS. As such, only the VCI for any one of the DL-CSISRS and the CSI-RS may be provided through higher layer signaling, andthe VCI for the other one may be determined based on the one to onemapping relationship. That is, the VCI for the DL-CSI SRS and the VCIfor the CSI-RS may be configured to have the same value. For example, arelationship of VCI_SRS^(DL) ₁=VCI_X₁, VCI_SRS^(DL) ₂=VCI_X₂, . . . maybe established.

Further, when VCI_X₁, . . . VCI_X_(P) are already configured as inEmbodiment 7-e, a one to one mapping relationship may be configuredwithout overlapping between an additional VCI X(s) for the CSI-RS andthe VCI_SRS^(DL). For example, a relationship of VCI_SRS^(DL)₁=VCI_X_(P+1), VCI_SRS^(DL) ₂=VCI_X_(P+2), . . . may be established.

Alternatively, when VCI_X₁, . . . VCI_X_(P) are already configured as inEmbodiment 7-e, parts thereof and the VCI_SRS^(DL) may be configured tohave the same values. Alternatively, parts of VCI_X₁, . . . VCI_X_(P)and the VCI_SRS^(DL) may be configured to have the same values, and theother parts of VCI_SRS^(DL) may be configured to have the same values asVCI_X_(P+1), VCI_X_(P+2), . . . .

When the VCI_SRS^(DL) is configured to have a one to one mappingrelationship with and the same values as the VCI_X as described above,only the mapping relationship may be configured between the VCI_X andthe VCI_SRS^(DL) and the VCI_SRS^(DL) may not be explicitly signaled.This scheme may correspond to a case in which CSI-RS based OLPC isapplied to a corresponding DL-CSI SRS based on a CSI-RS configurationusing a specific VCI_X.

Although the above various embodiments have been described separatelyfor clarity of explanation, two or more of the embodiments may beapplied in combination.

Embodiment 8

As proposed above in the previous embodiments, a VCI among parametersfor generating a base sequence of PUSCH DMRS/PUCCH DMRS, which aretransmitted through UE-specific higher layer signaling, may be denotedby n_(ID) ^(RS). If n_(ID) ^(RS) is configured through higher layersignaling, a group hopping pattern f_(gh), a sequence shift patternf_(ss), etc. are generated using corresponding values. If no n_(ID)^(RS) is provided through higher layer signaling, a PCI (i.e., N_(ID)^(cell)) may be used as in a legacy operation (see Equations 10 to 13and 17).

Specifically, a group hopping pattern f_(gh)(n_(s)) may be given asshown in Equation 7 equally for the PUSCH and the PUCCH. Here, in thepseudo-random sequence c(i) of Equation 7, the pseudo-random sequencegenerator may be initialized to c_(init) as shown in Equation 22 at thebeginning of each radio frame.

$\begin{matrix}{c_{init} = \left\lfloor \frac{n_{ID}^{RS}}{30} \right\rfloor} & \left\lbrack {{Equation}\mspace{14mu} 22} \right\rbrack\end{matrix}$

In Equation 22, n_(ID) ^(RS) is determined as N_(ID) ^(cell) if no valuefor n_(ID) ^(RS) is configured by a higher layer, or if a temporaryC-RNTI is used to transmit the most recent UL-related DCI for atransport block associated with corresponding PUSCH transmission.Otherwise (e.g., if a value of n_(ID) ^(RS) is configured by a higherlayer), the configured n_(ID) ^(RS) value may be applied.

Meanwhile, the sequence shift pattern f_(ss) may be defined differentlyfor the PUCCH and the PUSCH.

In the case of PUCCH, a sequence shift pattern f_(ss) ^(PUCCH) may bedefined as shown in Equation.f _(ss) ^(PUCCH) =n _(ID) ^(RS) mod 30  [Equation 23]

In Equation 23, n_(ID) ^(RS) is determined as n_(ID) ^(cell) if no valuefor n_(ID) ^(RS) is configured by a higher layer. Otherwise (e.g., if avalue of n_(ID) ^(RS) is configured by a higher layer), the configuredn_(ID) ^(RS) value may be applied.

In the case of PUSCH, f_(ss) ^(PUSCH) is defined as shown in Equation 12if no value for n_(ID) ^(RS) is configured by a higher layer, or if atemporary C-RNTI is used to transmit the most recent UL-related DCI fora transport block associated with corresponding PUSCH transmission.Otherwise (e.g., if a value of n_(ID) ^(RS) is configured by a higherlayer), f_(ss) ^(PUSCH) may be determined as shown in Equation 24.f _(ss) ^(PUSCH) =n _(ID) ^(RS) mod 30  [Equation 24]

In the case of SRS, a legacy operation follows a PUCCH sequence groupnumber to generate a base sequence thereof (see the paragraph aboveEquation 18). This means that the base sequence is generated using a PCI(i.e., N_(ID) ^(cell)). According to the present invention, in aspecific condition, e.g., when a VCI (n_(ID) ^(RS)) for the PUSCH or thePUCCH is configured through higher layer signaling, the SRS sequence maybe generated using the VCI instead of the PCI. Here, a VCI for the SRSmay be separately configured through UE-specific higher layer signaling,or configured to use another VCI (e.g., a VCI for a PUSCH, a VCI for aPUCCH, a VCI for a specific PUCCH format or a VCI configured for PUCCHformat 1a/1b triggered by an ePDCCH for ACK/NACK transmission).

For example, if no value for n_(ID) ^(RS) for the PUSCH or the PUCCH isconfigured by a higher layer, or if a temporary C-RNTI is used totransmit the most recent UL-related DCI for a transport block associatedwith corresponding PUSCH transmission, SRS sequence generation may beperformed according to the legacy operation (see the paragraph aboveEquation 18, Equation 18 and the paragraph below Equation 18).

Otherwise (e.g., if a value of n_(ID) ^(RS) for the PUSCH is configuredby a higher layer), a base sequence index u may be generated using theVCI for the PUSCH (e.g., ranging from 0 to 509 as described above inEmbodiment 2). Further, if sequence hopping is enabled, the PCI amongparameters used to determine a base sequence number v may be replacedwith the VCI for the PUSCH. Even in the case of f_(ss) ^(PUSCH), aresult calculated using the VCI for the PUSCH as shown in Equation 24may be used for SRS sequence generation. Alternatively, when the VCI forthe PUCCH is used for SRS sequence generation, u and v may be determinedusing the VCI for the PUCCH.

If the VCI for the SRS is signaled in addition to the VCI for thePUSCH/the VCI for the PUCCH, SRS sequence generation may be defined asdescribed below.

For SRS sequence generation, if VCI_SRS (e.g., ranging from 0 to 509) isconfigured by a higher layer, a group hopping pattern f_(gh) and asequence shift pattern f_(ss) may be defined as shown in Equation 25.u=(f _(gh)(n _(s))+f _(ss) _(_) _(SRS))mod 30  [Equation 25]

In Equation 25, an initialization parameter of f_(gh)(n_(s)) may bedefined as c_(init)=floor(VCI_SRS/30), and f_(ss) _(_) _(SRS)=VCI_SRSmod 30 may be defined.

Further, an initialization parameter c_(init) of a sequence hoppingpattern may be defined as shown in Equation 26.

$\begin{matrix}{c_{init} = {{\left\lfloor \frac{n_{ID}^{cell}}{30} \right\rfloor \cdot 2^{5}} + f_{{ss}\;\_\;{SRS}}}} & \left\lbrack {{Equation}\mspace{14mu} 26} \right\rbrack\end{matrix}$

In Equation 26, n_(ID) ^(cell) is VCI_SRS.

Alternatively, the initialization parameter c_(init) of the sequencehopping pattern may be defined as shown in Equation 27.

$\begin{matrix}{\left. {c_{init} = {{\left\lfloor \frac{n_{ID}^{cell}}{30} \right\rfloor \cdot 2^{5}} + \left( {n_{ID}^{cell}{mod}\; 30} \right) + \Delta_{ss}}} \right){mod}\; 30} & \left\lbrack {{Equation}\mspace{14mu} 27} \right\rbrack\end{matrix}$

In Equation 27, n_(ID) ^(cell) is VCI_SRS. Further, Δ_(ss)ϵ{0, 1, . . ., 29} may be defined as a parameter cell-specifically given by acorresponding DL serving cell.

Alternatively, the base sequence number u may be generated using a VCIfor a PUCCH, a VCI for a specific PUCCH format or a VCI separatelyconfigured for PUCCH format 1a/1b triggered by an ePDCCH for ACK/NACKtransmission.

Further, the above-described proposals of the present invention about anoperation for performing SRS sequence generation using a VCI for a PUSCHor a VCI for a PUCCH, or using a VCI for an SRS may be appliedindividually for a periodic SRS (P-SRS) configuration and an aperiodicSRS (A-SRS) configuration. For example, an independent VCI(s) may beconfigured for each of a plurality of SRS configurations (one P-SRSconfiguration may be present, and one or more A-SRS configurations maybe present for each DCI format), a commonly applicable VCI(s) may beconfigured for some SRS configurations, or a default ID (e.g., PCI) maybe configured for the SRS configurations.

In this case, if the VCI for the PUSCH or the VCI for the PUCCH issignaled by a higher layer, determination and application of a VCI to beused for SRS sequence generation may be enabled per an SRSconfiguration. Alternatively, determination and application of a VCI tobe used for SRS sequence generation may be enabled through individualsignaling or according to a separate rule for each SRS configuration.

A description is now given of specific embodiments of an operation fordetermining a parameter to be used for SRS sequence generation, and anoperation for generating an SRS sequence using the parameter, based onthe above description.

Embodiment 8-A

If both VCI_PUSCH (e.g., ranging from 0 to 509) and VCI_PUCCH (e.g.,ranging from 0 to 503) are configured through UE-specific higher layersignaling, an SRS sequence may be generated as described below.

For SRS sequence generation, a group hopping base sequence number isdefined as u=(f_(gh)(n_(s))+f_(ss))mod 30. Here, an initializationparameter of a group hopping pattern f_(gh)(n_(s)) is defined usingVCI_PUCCH as c_(init)=floor(VCI_PUCCH/30), and f_(ss)=VCI_PUCCH mod 30is defined.

For SRS sequence generation, an initialization parameter of a sequencehopping pattern is defined using VCI_PUSCH for the PUSCH asc_(init)={floor(VCI_PUSCH/30)}2⁵+f_(ss) _(_) _(PUSCH), and f_(ss) _(_)_(PUSCH)=VCI_PUSCH mod 30 is defined.

Here, VCI_PUCCH may be a VCI commonly applied to all PUCCH formats.Alternatively, VCI_PUCCH may be a VCI commonly applied only to one orsome PUCCH formats. Otherwise, VCI_PUCCH may be a VCI applied to aspecific PUCCH format(s) triggered by a legacy PDCCH or an ePDCCH forACK/NACK transmission.

Embodiment 8-A-i

VCI_PUCCH applied in Embodiment 8-A may be restricted to a VCIconfigured to be used only for a specific PUCCH format(s) (or only forPUCCH format 1a/1b triggered by an ePDCCH for ACK/NACK transmission). Adescription is now given of specific embodiments thereof.

Embodiment 8-A-i-a

VCI_PUCCH1a1b3 (e.g., ranging from 0 to 503) for dynamic PUCCH format1a/1b/3 and VCI_PUCCH1a1b22a2b (e.g., ranging from 0 to 509) forsemi-static PUCCH format 1a/1b/2/2a/2b may be configured throughUE-specific RRC signaling. In this case, SRS sequence generation may bedefined as described below.

If both VCI_PUSCH (e.g., ranging from 0 to 509) and VCI_PUCCH1a1b3(e.g., ranging from 0 to 503) are configured through UE-specific higherlayer signaling, an SRS sequence may be generated as described below.

For SRS sequence generation, a group hopping base sequence number isdefined as u=(f_(gh)(n_(s))+f_(ss))mod 30. Here, an initializationparameter of a group hopping pattern f_(gh)(n_(s)) is defined usingVCI_PUCCH1a1b3 as c_(init)=floor(VCI_PUCCH1a1b3/30), andf_(ss)=VCI_PUCCH1a1b3 mod 30 is defined.

For SRS sequence generation, an initialization parameter of a sequencehopping pattern is defined using VCI_PUSCH for the PUSCH asc_(init)={floor(VCI_PUSCH/30)}2⁵+f_(ss) _(_) _(PUSCH), and f_(ss) _(_)_(PUSCH)=VCI_PUSCH mod 30 is defined.

Embodiment 8-A-i-b

In the SRS sequence generation method defined in Embodiment 8-A-i-a,VCI_PUCCH3 for PUCCH format 3 and VCI_PUCCH1a1b for PUCCH format 1a/1bmay be may be separately configured through UE-specific RRC signaling.In this case, SRS sequence generation may be defined as described below.

If both VCI_PUSCH (e.g., ranging from 0 to 509) and VCI_PUCCH1a1b (e.g.,ranging from 0 to 503) are configured through UE-specific higher layersignaling, an SRS sequence may be generated as described below.

For SRS sequence generation, a group hopping base sequence number isdefined as u=(f_(gh)(n_(s))+f_(ss))mod 30. Here, an initializationparameter of a group hopping pattern f_(gh)(n_(s)) is defined usingVCI_PUCCH1a1b as c_(init)=floor(VCI_PUCCH1a1b/30), andf_(ss)=VCI_PUCCH1a1b mod 30 is defined.

For SRS sequence generation, an initialization parameter of a sequencehopping pattern is defined using VCI_PUSCH for the PUSCH asc_(init)={floor(VCI_PUSCH/30)}2⁵+f_(ss) _(_) _(PUSCH), and f_(ss) _(_)_(PUSCH)=VCI_PUSCH mod 30 is defined.

Embodiment 8-A-i-c

As in Embodiment 8-A-i-b, VCI_PUCCH3 for PUCCH format 3 andVCI_PUCCH1a1b for PUCCH format 1a/1b may be may be separately configuredthrough UE-specific RRC signaling. In this case, SRS sequence generationmay be defined as described below.

If both VCI_PUSCH (e.g., ranging from 0 to 509) and VCI_PUCCH3 (e.g.,ranging from 0 to 503) are configured through UE-specific higher layersignaling, an SRS sequence may be generated as described below.

For SRS sequence generation, a group hopping base sequence number isdefined as u=(f_(gh)(n_(s))+f_(ss))mod 30. Here, an initializationparameter of a group hopping pattern f_(gh)(n_(s)) is defined usingVCI_PUCCH3 as c_(init)=floor(VCI_PUCCH3/30), and f_(ss)=VCI_PUCCH3 mod30 is defined.

For SRS sequence generation, an initialization parameter of a sequencehopping pattern is defined using VCI_PUSCH for the PUSCH asc_(init)={floor(VCI_PUSCH/30)}2⁵+f_(ss) _(_) _(PUSCH), and f_(ss) _(_)_(PUSCH)=VCI_PUSCH mod 30 is defined.

Embodiment 8-A-i-d

VCI_PUCCH1a1b_ePDCCH for PUCCH format 1a/1b triggered by an ePDCCH forACK/NACK transmission may be configured through UE-specific RRCsignaling separately from other VCIs. In this case, SRS sequencegeneration may be defined as described below.

If both VCI_PUSCH (e.g., ranging from 0 to 509) and VCI_PUCCH1a1b_ePDCCH(e.g., ranging from 0 to 503) are configured through UE-specific higherlayer signaling, an SRS sequence may be generated as described below.

For SRS sequence generation, a group hopping base sequence number isdefined as u=(f_(gh)(n_(s))+f_(ss))mod 30. Here, an initializationparameter of a group hopping pattern f_(gh)(n_(s)) is defined usingVCI_PUCCH1a1b_ePDCCH as c_(init)=floor(VCI_PUCCH1a1b_ePDCCH/30), andf_(ss)=VCI_PUCCH1a1b_ePDCCH mod 30 is defined.

For SRS sequence generation, an initialization parameter of a sequencehopping pattern is defined using VCI_PUSCH for the PUSCH asc_(init)={floor(VCI_PUSCH/30)}2⁵+f_(ss) _(_) _(PUSCH), and f_(ss) _(_)_(PUSCH)=VCI_PUSCH mod 30 is defined.

Only one of the various methods of Embodiment 8-A-i may be defined andapplied all the time, or all or a part of the methods proposed inEmbodiments 8-A-i-a to 8-A-i-d may be enabled/disabled through higherlayer signaling or dynamic signaling.

Embodiment 8-A-ii

In Embodiment 8-A, a plurality of VCI_PUSCH values may be present (e.g.,VCI_PUSCH(1), VCI_PUSCH(2), . . . ). When a plurality of VCI_PUSCHvalues are UE-specifically configured as described above, VCI_PUSCH(n)may be applied among them.

For example, in Embodiments 8-A-i-a to 8-A-i-d, VCI_PUSCH may bereplaced with VCI_PUSCH(n) and a repeated description therebetween isnot given here. Here, information indicating whether to use a certainVCI_PUSCH(n) value for SRS sequence generation among a plurality ofVCI_PUSCH values signaled by a higher layer may be provided throughhigher layer signaling or dynamic signaling. Moreover, a singleVCI_PUSCH(n) value to be used for SRS sequence generation may beindicated among the VCI_PUSCH values, or a plurality of VCI_PUSCH(n)values may be indicated to enable generation of a plurality of SRSsequences.

Embodiment 8-B

In Embodiment 8-A, only VCI_PUSCH (e.g., ranging from 0 to 509) appliedto a PUSCH DMRS may be configured through UE-specific RRC signaling.That is, a description is now given of an SRS sequence generation methodin a case in which VCI_PUCCH is not separately signaled and VCI_PUSCH issignaled. For clarity of explanation, the following description isfocused on one VCI_PUSCH value. However, the following description maybe equally applied to a case in which a plurality of VCI_PUSCH valuesare signaled by a higher layer and one or more VCI_PUSCH(n) values amongthem are used for SRS sequences generation. Thus, generation of one ormore SRS sequences may be enabled.

For SRS sequence generation, a group hopping base sequence number isdefined as u=(f_(gh)(n_(s))+f_(ss))mod 30. Here, an initializationparameter of a group hopping pattern f_(gh)(n_(s)) is defined using aPCI of a DL serving cell as c_(init)=floor(PCI/30), and f_(ss)=PCI mod30 is defined.

For SRS sequence generation, an initialization parameter of a sequencehopping pattern is defined using VCI_PUSCH for the PUSCH asc_(init)={floor(VCI_PUSCH/30)}2⁵+f_(ss) _(_) _(PUSCH), and f_(ss) _(_)_(PUSCH)=VCI_PUSCH mod 30 is defined.

Embodiment 8-C

In Embodiment 8-A, only VCI_PUCCH (e.g., ranging from 0 to 503) appliedto a PUCCH DMRS may be configured through UE-specific RRC signaling.That is, a description is now given of an SRS sequence generation methodin a case in which VCI_PUSCH is not separately signaled and VCI_PUCCH issignaled. For clarity of explanation, the following description isfocused on one VCI_PUCCH value. However, if specific types of VCI_PUCCH(e.g., VCI_PUCCH1a1b3, VCI_PUCCH1a1b, VCI_PUCCH3 andVCI_PUCCH1a1b_ePDCCH) are configured through higher layer signaling asdescribed above in Embodiments 8-A-i-a to 8-A-i-d, the followingdescription may be equally applied to a case in which the specific typesof VCI_PUCCH are used for SRS sequences generation.

For SRS sequence generation, a group hopping base sequence number isdefined as u=(f_(gh)(n_(s))+f_(ss))mod 30. Here, an initializationparameter of a group hopping pattern f_(gh)(n_(s)) is defined usingVCI_PUCCH as c_(init)=floor(VCI_PUCCH/30), and f_(ss)=VCI_PUCCH mod 30is defined.

For SRS sequence generation, an initialization parameter of a sequencehopping pattern is defined using a PCI of a DL serving cell asc_(init)={floor(PCI/30)}2⁵+f_(ss) _(_) _(PUSCH), and f_(ss) _(_)_(PUSCH)={(PCI mod 30)+Δ_(ss)} mod 30 is defined.

Embodiment 8-D

A description is now given of SRS sequence generation in a case in whichΔ_(ss) (e.g., ranging from 0 to 29) is configured instead of VCI_PUSCH(e.g., ranging from 0 to 509) through higher layer signaling. In thiscase, it is assumed that VCI_PUCCH is signaled by a higher layer(particularly, case of Embodiment 8-B). In this case, in Embodiments 8-Ato 8-C, the parameter VCI_PUSCH may be replaced with VCI_PUCCH. Further,f_(ss) _(_) _(PUSCH) defined in association with a sequence hoppingpattern may be defined as f_(ss) _(_) _(PUSCH)={(VCI_PUCCH mod30)+Δ_(ss)} mod 30.

Moreover, if specific types of VCI_PUCCH (e.g., VCI_PUCCH1a1b3,VCI_PUCCH1a1b, VCI_PUCCH3 and VCI_PUCCH1a1b_ePDCCH) are configuredthrough higher layer signaling as described above in Embodiments 8-A-i-ato 8-A-i-d, the specific types of VCI_PUCCH may be used for SRSsequences generation. Further, if a plurality of Δ_(ss) values, e.g.,Δ_(ss)(1), Δ_(ss)(2), . . . , are signaled instead of a plurality ofVCI_PUSCH values by a higher layer, one or more Δ_(ss)(n) values amongthem may be used for SRS sequence generation and thus generation of oneor more SRS sequences may be enabled.

Embodiment 8-E

The DL-CSI SRS sequence generation method described above at thebeginning of Embodiment 8 may be defined to be triggered by a specificA-SRS configuration(s). In this case, a DL-CSI SRS sequence may begenerated using a parameter included in an A-SRS configuration(s). Forexample, only VCI_PUCCH_ASRS (e.g., ranging from 0 to 503) used tocalculate the initialization parameter of the group hopping patternf_(gh)(n_(s)), only VCI_PUSCH_ASRS (e.g., ranging from 0 to 509) used tocalculate the initialization parameter of the sequence hopping pattern,or both VCI_PUCCH_ASRS and VCI_PUSCH_ASRS may be included in a specificA-SRS configuration(s). Here, instead of the VCI_PUSCH_ASRS parameter,Δ_(ss) (e.g., ranging from 0 to 29) may be used for signaling asdescribed above in Embodiment 8-D.

As such, if VCI_PUCCH_ASRS and/or VCI_PUSCH_ASRS (or Δ_(ss)) areincluded in the A-SRS configuration(s), it may be defined topreferentially apply VCI_PUCCH_ASRS and/or VCI_PUSCH_ASRS (or Δ_(ss))rather than already defined other parameters to generate and transmit anA-SRS sequence according to a corresponding A-SRS configuration.

Further, the A-SRS configuration(s) for the DL-CSI SRS may be defined tobe tied with a CSI-RS configuration(s). In this case, in Embodiments 8-Ato 8-D, VCI_PUCCH may be replaced with a CSI-RS sequence scramblingvalue (or VCI_X) included in the CSI-RS configuration(s). If Δ_(ss)(e.g., ranging from 0 to 29) is included in the A-SRS configuration(s),VCI_PUCCH may be replaced with X as described above in Embodiment 8-D,and f_(ss) _(_) _(PUSCH) may be defined as f_(ss) _(_) _(PUSCH)={(X mod30)+Δ_(ss)} mod 30. In addition, Δ_(ss) may not be included in the A-SRSconfiguration(s) of the DL-CSI SRS, and it may be defined to applyΔ_(ss) of a DL serving cell. Alternatively, it may be defined to assumeΔ_(ss)=0, and this can be applicable only when a network has configuredΔ_(ss)=0 cell-specifically.

In addition, a parameter for the DL-CSI SRS may not be separatelyconfigured, SRS sequence generation for A-SRS transmission may bedefined to be the same as SRS sequence generation for UL-CSI SRStransmission according to the method proposed in Embodiments 8-A to 8-D.That is, a general SRS (i.e., a UL-CSI acquisition SRS tied with PC ofPUSCH with a predetermined difference value) sequence generation methodmay be equally applied as the SRS sequence generation method of theDL-CSI acquisition A-SRS. At this time, although Tx power of the DL-CSISRS may be different from Tx power of the UL-CSI SRS, the same sequencegeneration method may be applied. In this case, a sequence of SRSsreceived from other legacy UEs received in the same band in a cell(s) towhich the DL-CSI acquisition A-SRS is directed may not be orthogonallypaired with the DL-CSI acquisition A-SRS. Even in this case, since theDL-CSI acquisition A-SRS is rarely transmitted compared to a generalSRS, the A-SRS may be transmitted by forming orthogonal pairing with anSRS transmitted by an enhanced UE (i.e., UE operating according to 3GPPLTE Release 11 and subsequent releases) without supporting orthogonalpairing with an SRS of a legacy UE.

Although a method for generating and transmitting a sequence byconfiguring and applying an RS parameter set capable of efficientlysupporting CoMP operation for a PUSCH DMRS, a PUCCH DMRS, an SRS (UL-CSISRS and DL-CSI SRS), a CSI-RS and a UE-specific RS has been describedabove, the scope of the present invention is not limited there to andthe principle of the present invention is also applicable to a methodfor generating and transmitting a sequence of other UL RSs and/or DLRSs.

FIG. 13 is a flowchart of a method for transmitting and receiving an RS,according to an embodiment of the present invention.

In step S1310, a UE may receive an RS parameter set (e.g., VCI) forgenerating an RS sequence from a network (e.g., eNB).

The RS parameter set may be independently signaled per an RS type, ormay be signaled as information commonly applied to different RS types.

Further, the RS parameter set may be explicitly signaled for a specificRS type, or may be implicitly determined based on an RS parameter setfor another RS type. For example, a first RS parameter set for a firstRS may be explicitly signaled, and a second RS parameter for a second RSmay be implicitly determined based on the first RS parameter accordingto a predetermined mapping rule (e.g., one to one mapping rule).Alternatively, the second RS parameter may be implicitly determinedbased on first and third RS parameter sets for first and third RSs.

In addition, RS parameter set candidates may be provided through higherlayer signaling (e.g., RRC signaling), and an RS parameter set to beused for RS sequence generation may be indicated among the candidatesthrough dynamic signaling (e.g., signaling based on information includedin PDCCH DCI).

The definition, configuration and signaling methods of the RS parameterset may follow the above-described embodiments of the present invention,and repeated descriptions thereof are not given here.

In step S1320, the UE may generate a sequence of a corresponding type RSbased on the received RS parameter set.

In step S1330, the UE may transmit the generated RS to the network(e.g., one or more RPs).

Although not described above in relation to FIG. 13, the UE may performan operation for detecting and receiving a DL RS (e.g., CSI-RS orUE-specific RS) using the RS parameter received in step S1310. Forexample, the UE may explicitly receive an RS parameter set for a DL RSfrom the network or implicitly determine the RS parameter set based onan RS parameter for another type RS, assume that the network (e.g., oneor more TPs) has generated and transmitted the DL RS based on thedetermined RS parameter, and correctly detect and receive the DL RSbased on the assumption.

Meanwhile, an eNB may assume that the UE has generated an RS accordingto the RS sequence generation method proposed by the present invention,and detect the RS transmitted by the UE based on the assumption.

The above-described embodiments of the present invention may be appliedindependently or two or more embodiments may be simultaneously applied,and repeated descriptions thereof are not given here for clarity.

FIG. 14 is a block diagram of a UE 10 and an eNB 20 according to anembodiment of the present invention.

Referring to FIG. 14, the UE 10 may include a transmitter 11, a receiver12, a processor 13, a memory 14 and a plurality of antennas 15. Theantennas 15 refer to terminal devices supporting MIMO transmission andreception. The transmitter 11 may transmit various signals, data andinformation to an external device (e.g., eNB). The receiver 12 mayreceive various signals, data and information from the external device(e.g., eNB). The processor 13 may provide overall control to the UE 10.

The UE 10 may be configured to transmit an uplink signal. The processor13 of the UE 10 may be configured to receive an RS parameter set usingthe receiver 12, generate an RS based on the RS parameter set, andtransmit the generated RS to the eNB 20. The definition, configurationand signaling methods of the RS parameter set and the RS generation andtransmission methods may follow the above-described embodiments of thepresent invention, and repeated descriptions thereof are not given here.

In addition, the processor 13 of the UE 10 may process informationreceived by the UE 10, information to be transmitted to an externaldevice, etc. The memory 14 may store the processed information for apredetermined time and may be replaced with a component such as a buffer(not shown).

The above configuration of the UE 10 can be implemented in such a mannerthat the above-described embodiments of the present invention areapplied independently or two or more embodiments are simultaneouslyapplied thereto, and repeated descriptions thereof are not given herefor clarity.

The eNB 20 may include a transmitter 21, a receiver 22, a processor 23,a memory 24 and a plurality of antennas 25. The processor 23 of the eNB20 may be configured to assume that the UE 10 has generated an RSaccording to the RS sequence generation method proposed by the presentinvention, and detect the RS transmitted by the UE based on theassumption.

An eNB is exemplified as a downlink transmission entity or an uplinkreception entity and a UE is exemplified as a downlink reception entityor an uplink transmission entity to describe the embodiments of thepresent invention, but the scope of the present invention is not limitedthereto. For example, the description of the eNB may be equally appliedto a case in which a cell, an antenna port, an antenna port group, anRRH, a transmission point, a reception point, an access point or a relaynode serves as an entity of downlink transmission to a UE or an entityof uplink reception from the UE. Further, the principle of the presentinvention described through the various embodiment of the presentinvention may be equally applied to a case in which a relay node servesas an entity of downlink transmission to a UE or an entity of uplinkreception from the UE or a case in which a relay node serves as anentity of uplink transmission to an eNB or an entity of downlinkreception from the eNB.

The embodiments of the present invention may be implemented by variousmeans, for example, hardware, firmware, software, or combinationsthereof.

When the embodiments of the present invention are implemented usinghardware, the embodiments may be implemented using at least one ofApplication Specific Integrated Circuits (ASICs), Digital SignalProcessors (DSPs), Digital Signal Processing Devices (DSPDs),Programmable Logic Devices (PLDs), Field Programmable Gate Arrays(FPGAs), processors, controllers, microcontrollers, microprocessors,etc.

In a firmware or software configuration, the embodiments of the presentinvention may be implemented in the form of a module, a procedure, afunction, etc. For example, software code may be stored in a memory unitand executed by a processor. The memory unit is located at the interioror exterior of the processor and may transmit and receive data to andfrom the processor via various known means.

The detailed description of the preferred embodiments of the presentinvention is given to enable those skilled in the art to realize andimplement the present invention. While the present invention has beendescribed referring to the preferred embodiments of the presentinvention, those skilled in the art will appreciate that manymodifications and changes can be made to the present invention withoutdeparting from the spirit and essential characteristics of the presentinvention. For example, the structures of the above-describedembodiments of the present invention can be used in combination. Theabove embodiments are therefore to be construed in all aspects asillustrative and not restrictive. Therefore, the present inventionintends not to limit the embodiments disclosed herein but to give abroadest range matching the principles and new features disclosedherein.

Those skilled in the art will appreciate that the present invention maybe carried out in other specific ways than those set forth hereinwithout departing from the spirit and essential characteristics of thepresent invention. The above embodiments are therefore to be construedin all aspects as illustrative and not restrictive. The scope of theinvention should be determined by the appended claims and their legalequivalents, not by the above description, and all changes coming withinthe meaning and equivalency range of the appended claims are intended tobe embraced therein. Therefore, the present invention intends not tolimit the embodiments disclosed herein but to give a broadest rangematching the principles and new features disclosed herein. It is obviousto those skilled in the art that claims that are not explicitly cited ineach other in the appended claims may be presented in combination as anembodiment of the present invention or included as a new claim by asubsequent amendment after the application is filed.

INDUSTRIAL APPLICABILITY

The above-described embodiments of the present invention are applicableto various mobile communication systems.

The invention claimed is:
 1. A method for transmitting an uplink signalby a User Equipment (UE) in a wireless communication system, the methodcomprising: receiving a plurality of parameter sets for a plurality ofDemodulation Reference Signals (DMRSs), the plurality of DMRSs includinga Physical Uplink Shared Channel Demodulation Reference Signal (PUSCHDMRS) and a Physical Uplink Control Channel Demodulation ReferenceSignal (PUCCH DMRS); and transmitting a sequence of the PUSCH DMRS orthe PUCCH DMRS generated by using one parameter set among the parametersets, wherein each of the parameter sets comprises a virtual cellidentifier (VCI) value, and wherein a first VCI range for selecting aPhysical Uplink Shared Channel Demodulation Reference Signal VirtualCell Identifier (PUSCH DMRS VCI) value is wider than a second VCI rangefor selecting a Physical Uplink Control Channel Demodulation ReferenceSignal Virtual Cell Identifier (PUCCH DMRS VCI) value.
 2. The methodaccording to claim 1, wherein the parameter sets comprise a plurality ofPUSCH DMRS parameter sets corresponding to a plurality of receptionpoints (RPs) to which the PUSCH DMRS is directed.
 3. The methodaccording to claim 1, wherein the parameter sets comprise a plurality ofPUSCH DMRS parameter sets corresponding to a plurality of PUCCH formatgroups.
 4. The method according to claim 1, further comprising:receiving a plurality of Sounding Reference Signal (SRS) parameter setscorresponding to a plurality of SRS power control processes.
 5. Themethod according to claim 1, wherein reception points to which thesequence is directed have different physical cell identifiers (PCIs),and values obtained by an equation ‘floor(PCI/30)’ for the differentPCIs are the same.
 6. The method according to claim 1, wherein each ofthe parameter sets comprises a sequence shift offset (Δ_(ss))individually applied to the parameter sets.
 7. The method according toclaim 1, wherein each of the parameter sets comprises a parametercommonly applied and a parameter individually applied within each of theparameter sets.
 8. The method according to claim 1, wherein the firstVCI range corresponds to ‘0 to 509’ and the second VCI range correspondsto ‘0 to 503’.
 9. The method according to claim 8, wherein a parameterset for the PUSCH DMRS does not comprise a sequence shift offset(Δ_(ss)).
 10. The method according to claim 1, wherein the parametersets are provided through higher layer signaling.
 11. A User Equipment(UE) for transmitting an uplink signal, the UE comprising: a receiverconfigured to receive a plurality of parameter sets for a plurality ofDemodulation Reference Signals (DMRSs), the plurality of DMRSs includinga Physical Uplink Shared Channel Demodulation Reference Signal (PUSCHDMRS) and a Physical Uplink Control Channel DMRS Demodulation ReferenceSignal (PUCCH DMRS); a processor configured to generate a sequence ofthe PUSCH DMRS or the PUCCH DMRS using one parameter set among theparameter sets; and a transmitter configured to transmit the sequence,wherein each of the parameter sets comprises a virtual cell identifier(VCI) value, and wherein a first VCI range for selecting a PhysicalUplink Shared Channel Demodulation Reference Signal Virtual CellIdentifier (PUSCH DMRS VCI) value is wider than a second VCI range forselecting a Physical Uplink Control Channel Demodulation ReferenceSignal Virtual Cell Identifier (PUCCH DMRS VCI) value.
 12. The UEaccording to claim 11, wherein the first VCI range corresponds to ‘0 to509’ and the second VCI range corresponds to ‘0 to 503’.
 13. The UEaccording to claim 11, wherein a parameter set for the PUSCH DMRS doesnot comprise a sequence shift offset (Δ_(ss)).
 14. The UE according toclaim 11, wherein the parameter sets are provided through higher layersignaling.